Journal Search Engine
Search Advanced Search Adode Reader(link)
Download PDF Export Citaion korean bibliography PMC previewer
ISSN : 1225-8504(Print)
ISSN : 2287-8165(Online)
Journal of the Korean Society of International Agricultue Vol.31 No.4 pp.359-377
DOI : https://doi.org/10.12719/KSIA.2019.31.4.359

Responses to Biotic and Abiotic Stresses and Transgenic Approaches in the Coffee Plant

Banavath Jayanna Naik, Seong-Cheol Kim, Min Ju Shin, Chun Whan Kim, Chan Kyu Lim, Hyun Joo An
Research Institute of Climate Change and Agriculture, NIHHS, RDA, Jeju 63240, Korea.
Corresponding author (Phone) +82-64-741-2560 (E-mail) kimsec@korea.kr
August 13, 2019 November 13, 2019 November 18, 2019

Abstract


Coffee (Coffea L.) belongs to the family Rubiaceae and is a main cash crop for tropical farmers. It has more quantity of medicinal value and protein (25–28%). As an environmentally sensitive crop, climate change has a significant impact on the quality and stable production of coffee. To develop abiotic baroreceptors on the tolerance response in coffee, tremendous research is going on to improve the productivity under varying degrees of stress at various growth stages. Physiological, morphological and biochemical parameters change the productivity and quality of coffee. This paper reviews some of the important aspects of biotic and abiotic tolerance in coffee. We explain the best implementation methods for the improvement of coffee production and briefly advantages or importance of coffee in medicinal values, significances of biotechnological aspects and genetic engineering approaches for crop improvements.



커피식물의 생물학적 및 비생물학적 스트레스에 대한 반응과 형질전환 연구

바 나바스 자이아나 나이크, 김 성철, 신 민주, 김 천환, 임 찬규, 안 현주
농촌진흥청 국립원예특작과학원 온난화대응농업연구소

초록


    INTRODUCTION

    Coffea arabica also called as the Arabian coffee belongs to the Rubiaceae family and natives to tropical crop. This coffee cultivation and production is present throughout the world but majorly present in Brazil, Vietnam, Colombia, and Indonesia. The global production of coffee is 168.87million bags (http://www.ico.org/). C. arabica is originated from Ethiopia and today it is grown around the world (Söndahl et al., 2005) and is the 2nd most commercial product followed by oil (Davis et al., 2012). South Korea’s coffee industry is also estimated at 6.8 trillion won in 2019. Korea is known a sixth consumption country in the world and an average adult drank average 353 cups in 2018 year (Park et al, 2019).

    C. arabica is the polyploidy species of the genus Coffea and it contains 4 copies of 11 chromosomes, hybridization between the diploids C. canephora and C. eugenioides (Lashermes et al., 1999). It can endure low temperatures, but not frost, and it does best with a medial temperature between 15 and 24°C (Taye Kufa Obso, 2006). These beans of normal C. arabica have twelve milligram / gram of caffeine in dry mass and it contains 0.76 mg / gram of caffeine with all the flavor of the standard coffee beverage (Silvarolla et al., 2004). Coffee contains most of the medicinal values which is useful for human health.

    Among some 90 species of the genus Coffea, due to disease and adaptability constraints and by other factors only two species are nowadays commercially grown worldwide, namely C. canephora (Robusta) will grow at low lands and C. arabica (Arabica) will grow at high lands altitude ranges between 1400 and 1800 m in tropical area (Da Matta & Ramalho, 2006;Dias et al., 2007; Hindorf et al., 2010; Davis et al. 2012). Due to some abnormal conditions (drought, high temperature, high cold and biotic stress), coffee production is going to decrease. To overcome these biotic and abiotic problems for mass production of high quality coffee breeding techniques MAS (Marker Assisted Selection) programme and genetic modifications techniques are useful. In this review, we discussed the impact of biotic and abiotic stress, the effect of environmental change on coffee plants and the genetic engineering approaches in coffee plants.

    Suitable conditions, plant morphology and habitat

    The temperature for the healthy survive of coffee plant is 15°C to 21°C and it can also tolerate the temperature up to 24°C. High temperature causes damage, eventually fruit set will be reduced. It needs both sun (not direct sun) and rain, needs shade in its growth phase when it starts the flowering and during fruit set (Franco, 1958;Camargo, 2010;Davis et al., 2012). Occurrence of frosts, even if sporadic, may strongly limit the economic success of the crop (Camargo, 1985;Camargo, 2009;Davis et al., 2012), moist and nutritionally rich soil, that is rapidly water storing and rapidly draining excess water from soil is suitable for the cultivation of coffee plants. Due to the rain falls and optimum temperature, the coffee plants were often planted on June to August. Lime will use in the soil to maintain pH 4.5 - 5.5. Coffee is a perennial bush with evergreen foliage, glossy appearance with main stem will grow vertically. Primary branches produce secondary, tertiary and lateral branches. In addition, some shoots arise from the main stem of the coffee plant and grow vertically; they are termed as ‘suckers' (Orthotropic shoots) and capable of forming a new bush by producing primary and secondary branches. The orthotropic shoots are also utilized for vegetative propagation. These plants develop very intense root system because of coffee roots expect more consumption of N, Ca, and Mg and its having self-pollination. Plants produce economic yields for 30 to 40 years on average with the height of 7-10 meters (Barwick et al., 2004). The plants, which will show the different morphology and physiology with high stress tolerant mechanism those varieties produce comparable yield under drought stress (Da Matta, 2004).

    Effect of drought and high temperature on coffee production

    Abiotic stress is the stress which can cause abnormal condition to plant by environmental factors like drought, high temperature, cold temperature, flooding, pollutants (ozone, sulfur dioxide), heavy metal and salt stress. Drought stress changes the physiology, morphology, metabolic, and molecular characters in plants. This stress occurs for several causes including limited rainfall and more intensity of light, evaporative demands and less wetness storage capacity of soils (Wery et al., 1994;Farooq et al., 2009;Salehi-Lisar et al., 2016). Drought can affect nearly every process in a plant, from energy production to grow and plants respond to drought stress through a variety of complex mechanisms (Levitt, 1980;Des Marais, 2017;Haile & Kang, 2018) and these coffee plants are more defenseless against to shortage of water stress during the propagative stages of extension (Growth), inflorescent and seed development. Consequently, plants will produce a few viable seeds (Tardieu et al., 2018). Limited water and unfavorable temperatures can arrest the plant metabolism and reduce the coffee yield.

    High temperature also cause the stress which will change the plant phenomics and the temperature and photoperiod determine the distribution of a plant species by acting directly through physiological constraints (Growth and reproduction) (Thomas et al., 2004;Menendez et al., 2006;Silva et al., 2008). High-temperature stress has a major influence on plant reproduction, particularly those of microsporogenesis and megasporogenesis, anthesis, pollination, pollen tube growth, fertilization, and early embryo development. These are all highly susceptible to high-temperature stress. Due to failure of the above processes, plants will be decreased fertilization or increased early embryo abortion, led to a lower number of grains and limited yield (Weis & Berry, 1988;Da Matta et al., 2006;Silva et al., 2008;Farooq et al., 2009;Maduraimuthu & Vara Prasad, 2014;Naveed et al., 2014). This stress alters membrane functions by altering membrane fluidity and plant cell membrane structure which is especially important for crucial processes like light reactions and respiration. The formation of the flower and modification of flower into fruit set can be delayed by continuous exposure to temperatures up to over 30°C (86°F) and eventually it can severely damage coffee plants by stunting growth, yellowing leaves, even spawning stem tumors (Maduraimuthu & Vara Prasad, 2014).

    In response to water limiting and high-temperature state, there is a change of gene expression will occur and it prompted by or operated by transcription factors (TFs). These TFs fasten to particular cis-elements to induce the expression of targeted stress-inducible genes, permitting for products to be transcribed that with stress response and tolerance (Nakashima et al., 2017), those includes DREB/ERF, AREBs, NAC, AP2/ERF, MYB, and WRKY. The cellular and signaling mechanism under the abiotic stress condition was shown in Fig.1.

    The effect of abiotic stress on the coffee plant physiological and biochemical system

    The abiotic stress (drought, salt, high temperature and cold) will change the plant physiological system including photosynthesis rate, chlorophyll content, stomatal index, specific leaf area, relative water content, water use efficiency, membrane stability and electrolyte leakage (Farooq et al. 2009;Mariga, 2016) hence plant cell may get damage and functions may not occur properly. The biochemical system in plants includes antioxidative enzymes (SOD, CAT, APX, and GR), proline, lipid peroxidation, total sugar levels, total amino acids, and soluble sugars are the major biochemical parameters in the plants system.

    Photosynthesis can enlarge the biomass of plants. High rate of light reaction occurs for the excessive metabolisms and physiological changes for the excessive carbon fixation capacity (Gulmon & Chu, 1981). Although, Light intensity is the one which can change the photosynthetic rate, by applying the different temperature regimes to plants we can select the plants which are having the best photosynthetic rate under the high temperature (Mazzafera & Warrior, 1991;Bote & Struik, 2011;Biruk Ayalew, 2018;Liu et al., 2018). Likewise, Bote et al. (2018) reported that beneath of full sunlight, arabica scored a less rate of light reaction compared to the plants which were not grown under sun light. High shading reduces both quantity and quality of the passing of the radiation, hence reduces the morphology and physiological characters of the plant such as light reaction and extension (Morais et al., 2003;Bote & Struik, 2011;Biruk Ayalew, 2018). Eventually it reduces the stomatal conductivity hence occurs the less CO2 intake and decline the light reaction of mesophyll cells by expose the plants to direct sun light and temperature (McDonald, 2003;Chastain et al., 2014;Tesfaye et al., 2014;Biruk Ayalew, 2018). Due to growing the plants under high shading climate it reduces the leaf surface temperature and leaf photosynthetic characteristics (Araujo et al., 2008;Steiman et al., 2011;Boreux et al., 2016;Liu et al., 2016; Nesper et al., 2017; Liu et al., 2018). Due to the decrease in the photosynthesis rate in plants automatically chlorophyll production also will be less, hence the plant's metabolism will become less compare to the plants which are having high photosynthetic rate coffee plants.

    Light and CO2 availability in the mesophyll of plant leaves are the main determinants of their net carbon assimilation rate. The coffee tree has low rates of net CO2 assimilation (A) ranges of 4-11 mmol m-2 s-1 with current natural atmospheric CO2 concentration. Da Matta et al. (2008) explained the rate of net carbondioxide assimilation by considering the ranges of stomatal conductance in arabica and conilon coffee. The average net carbondioxide assimilation (7.2 and 8.3 μmol m-2 s-1) was observed at 108 and 148 mmol m-2 s-1 of stomatal conductance. These two species determined the 30-40 μmol m-2 s-1 of photosynthesis under saturated light and CO2 (~5 kPa) (Almeida & Maestri, 1997;Campostrini & Maestri, 1998;Da Matta et al., 2001;Silva et al., 2004). The developing green coffee fruits are also having stomata for gas exchange. The berry photosynthesis rate was increased at the photosynthetic photon flux range between 0 and 200 μmol photons m-2 s-1, and were nearly saturated at above 500 μmol photons m-2 s-1 (Vaast et al., 2005). By using the growth analysis, Cannel (1985) was reported that the photosynthesis in fruits is third of their own dry matter gain. Reis et al. (2009) reported that the plants provided 300kg ha-1 of nitrogen showed high chlorophyll (72.78 μg L-1) content and photosynthesis rate (15.43 μmol CO2 m-2 s-1). Barros et al. (1999) was observed maximum rate of photosynthesis (4.5 mg CO2 dm-2 h-1) and decreasing of photosynthesis by decreasing the stomatal conductance at midday. This is associated to stomatal closer induced by direct sun light in coffee plants. Ramalho et al. (2018) was reported that photosynthesis rate in three coffee species of ‘Apoata’, ‘Icatu’ and ‘Obata’ (2.8 μmol CO2 m-2 s-1, 2 μmol CO2 m-2 s-1 and 1.9 μmol CO2 m-2 s-1) under drought and cold stress. Similarly, Pompelli et al. (2010) was discussed about high photosynthesis rate (2.1±2 μmol CO2 m-2 s-1mol) under low light of low nitrogen (0 mmoles) and high nitrogen (23 mmoles) concentration. Kumar & Tieszen (1980) was observed that high photosynthesis rate (14 μmol CO2 m-2 s-1) under shade leaves than the sun light leaves. Similar results were also reported that photosynthetic rate will be high in shaded leaves than under sun light leaves of coffee plants (Kumar & Tieszen 1980;Kaniechi et al., 1995;Paiva et al., 2003;Bote et al., 2018).

    Stomata serve a very crucial function to plants, Stomata will get open during day time and close at the night time in coffee plants and they involve in the exchanging of gas, water transpiration and help for the photosynthesis to make energy for plant survival. Light, heat, water availability, atmospheric humidity, carbon dioxide concentration, and wind motions will directly affect stomatal movements (Martin et al., 1993;Kanechi et al., 1995;Wintgens, 2004;Taye Kufa & Jurgen Burkhardt, 2011). Leaves show a less stomatal opening due to the shortage of H2O 20 - 30 mg cm-2 of the surface of the leaf and close with a deficiency of about 80 mg cm-2 in coffee plant. The evaporation of water from the non-shaded coffee plant is approximately 6 g cm-2 (Ross-Karstens, 1998;Taye Kufa & Jurgen Burkhardt, 2011).

    The stomatal conductance values were low as 10-20 mmol m-2 s-1 during the afternoon. The decreasing of net CO2 assimilation rate in the afternoon has been associated with stomatal closure and also circumstantially with photo inhibition of photosynthesis (Da Matta et al., 2008). The coffee yields may decrease by increasing the more shade because of lower whole-tree carbon assimilation, that means more shade also will affect the coffee yield (Da Matta et al.,2008). The maximum and minimum stomatal densities were determined in full sunlight and moderate shade conditions respectively. In addition, the stomatal area index was significantly higher in sun-exposed leaves than in shaded leaves. Adugna & Paul (2011) was observed more stomatal conductance (100 mmol m-2 s-1) in shaded plants than the direct sun light (60 mmol m-2 s-1) plant leaves. Kumar & Tieszen (1980) and Kanechi et al. (1995) were observed lower stomatal conductance under sun light leaves due to increase of leaf temperature and vapor pressure. Similarly, Pompelli et al. (2010) was reported high stomatal conductance (19±0.7 mmol m−2 s−1 and 12±0.1 mmol m−2 s−1) at high light of high nitrogen and low nitrogen concentration.

    Water use efficiency (WUE) was found to be higher in dry sites than in the wet sites thus reflecting the availability of water. The WUE is generally high in drought and hightemperature tolerant coffee varieties because these tolerant coffee varieties produce deep root system for uptake the water from the root system (Burkhardt et al., 2006;Abraham & Dufera, 2017;Liu et al., 2018). WUE is positively correlated with transpiration because of the water loss and gas exchange will occur high, so, that photosynthesis rate will become high (Meinzer et al., 1990;Da Matta et al., 2000;Pinheiro et al., 2005;Da Matta et al., 2006;Bote & Struik, 2011;Haggar et al., 2012;Dong et al., 2016).

    Relative water content (RWC) is the method to check the water status for the physiological consequence of cellular water deficit and water potential as an estimate of the energy status of the plant. Water is more useful to explain the soil-plant–atmosphere condition. Water deficit plants contain more RWC in coffee plants under shade conditions to occur the freely plant metabolic mechanism (Nunes, 1976;Da Matta et al., 1993;Pinheiro et al., 2005;Pinheiro et al., 2005;Da Matta et al., 2006;Taye Kufa, 2006;Dias et al., 2007;Tounekti et al., 2018). High RWC increases photosynthesis through the chlorophyll content under stress conditions (Rodriguez et al. 2001;Matsumoto et al., 2006;Worku & Astatkie, 2010;Shimber et al., 2013). According to the Rodriguez et al. (2001) more relative water content was observed in the shaded plants than the direct sun light plants because the shaded plants contain more moisture content in soil and less transpiration from leaf. The chlorophyll content was also high in 70% sun light plants than the 100% sun light plants. Ramalho et al. (2018) was reported RWC in three coffee species of ‘Apoata’, ‘Icatu’ and ‘Obata’ (82.9±3%, 69.5 ± 3.4 % and 82.8±2.7%) under drought and cold stress, respectively. Haile & Kang (2018) was observed 74.6±1.80% of RWC in 40% deep sea water irrigated coffee seedlings.

    Specific leaf area is one which will use in growth analysis and it can explain the link of plant carbon (C) and water cycles because it describes the diffusion of leaf biomass relative to leaf area. The specific leaf area is strongly affected by drought, high temperature and light intensity (Casper et al., 2001;Reich et al., 2002;Marron et al., 2003;Laureano et al., 2008;Farooq et al., 2009;Kumar et al., 2012;Liu et al., 2017). Adugna & Paul (2011) was observed more specific leaf area (116 cm2 g−1) in shaded plants than the direct sun light (98 cm2 g−1) plants.

    Ion leakage is a good indication of the stress response in plant cells. This process widely used for the measurement of plant injury and plant stress tolerance (Levitt, 1972; Blum & Ebercon, 1981;Bajji et al., 2002; Demidchik et al., 2014). The accumulation of reactive oxygen species (ROS) in plant cell may lead to electrolyte leakage and often result in programmed cell death (Demidchik et al., 2014). The oozing of ions is specifically connected to potassium ions efflux from plant cells, which is mediated by plasma membrane cation conductance’s. Most probably the cation selectivity’s are encoded by GORK (Gated outwardly rectifier K+), SKOR (Stelar K+ outwardly rectifier), and annexin genes. CNG (Cyclic nucleotide-gated) and IGR (Ionotropic glutamate receptors) are ion channels also involved in ion movements. The general response of plant by drought, salt, and high-temperature flow chart was shown in Fig. 2. Haile & Kang (2018) was reported 90% of the electrolyte leakage in 40% deep sea water irrigated coffee seedlings. Similarly, Ursula et al. (1992) was observed 86% of the electrolyte leakage in response to water stress and gibberellic acid treated coffee plants. Chaves et al. (2017) was reported 3.8-4.0% of electrolyte leakage in seven years old of two-meter-tall coffee trees.

    Reactive oxygen species (ROS) are chemically reactive chemical species containing oxygen. ROS is a set of free radicals, ions, and molecules obtained from oxygen (O2) produced as byproducts of plant cellular metabolism. The most common ROS includes singlet oxygen (1O2), superoxide anion (O2•−), hydrogen peroxide (H2O2), and hydroxyl radical (•OH-). Environmental pressures lead to high production of ROS generates continuous oxidative damage eventually cell death. In plants, leakage of electrons into O2 from the electron transport activities of chloroplasts, mitochondria, peroxisomes and plasma membranes (Foyer et al., 1994;Foyer et al., 1997;Del Río et al., 2006). ROS reacts with macromolecules (lipids, proteins, and DNA) to make the cells functionally inactive by causing the oxidative damage (Hiramoto et al., 1998;Foyer & Fletcher, 2001;Farooq et al., 2009;Sharma et al., 2012). For control or cleave, these toxic substances (detoxification) production of antioxidative enzymes occur in the plant cells. (Yan et al., 2007;Farooq et al., 2009;Sharma et al., 2012;Banavath et al., 2018). Those antioxidative enzymes are SOD (superoxide dismutase), CAT (catalase), GPX (Glutathione peroxidase), enzymes of ascorbate-glutathione (AsA-GSH) cycle such APX (Ascorbate peroxidase), MDHAR (Mono dehydro ascorbate reductase), DHAR (Dehydro ascorbate reductase), GR (Glutathione reductase) and GSH (glutathione). Non-enzymatic antioxidants are carotenoids, tocopherols, and phenolics (Rinkus et al., 1990;Devasagayam et al., 1996;Noctor et al., 1998;Asada, 1999;Sharma et al., 2010;Sharma et al., 2012;Martini et al., 2016; Metro et al., 2017).

    Assemble of Proline in plant cell is one of the indication for the biochemical responses to various stress (biotic and abiotic) and it also involve in the developmental programme of generative tissues (e.g. pollen) (Chiang et al., 1995;Fabro et al., 2004;Verbruggen & Hermans, 2008). It acts as a multi-functional molecule and its defense by the stabilizing the protein structure by acts like molecular chaperon for the protecting the plant cell from the damaging effects of various environmental stresses. Besides acting as an excellent osmolyte, proline plays three major roles during stress, i.e. as a metal chelator, an antioxidative defense molecule and a signaling molecule (Jouve et al., 1993;Ashraf et al., 2007;Parvaiz & Satyawati, 2008;Szabados & Savouré, 2010;Palakolanu et al., 2011;Hayat et al., 2012;Koyro et al., 2012;De Carvalho et al., 2013;Banavath et al., 2018).

    Da Matta et al. (1997) reported that proline accumulation is in C. arabica and C. canephora species of ‘Catui’ (5.65 μmol g-1DM) and ‘Kouillou’ (8.24 μmol g-1DM) in winter season, however ‘Catui’ (2.15 μmol g-1DM) and ‘Kouillou’ (2.27 μmol g-1DM) in summer season, respectively. Similarly, Jouve et al. (1993) reported accumulation of more proline in micro cuttings of arabica and canephora under low temperature. According to Mazzafera & Teixeira (1989), proline accumulation in drought-stressed plants of arabica coffee is more directly related to injury imposed by water limitation rather than being a defense mechanism against drought stress.

    Soluble sugars are an important compound in maintain the fruitful structure and growth of the plants by participating in regulation of growth, light reaction, partitioning of carbon, metabolism of carbohydrate and lipids, osmotic homeostasis, protein synthesis and flowering, senescence, gene expression and stabilization of membranes during various abiotic stresses in coffee plants (Koch, 1996;Sheen et al., 1999;Smeekens, 2000;Hoekstra et al., 2001;Rolland & Sheen, 2006;Rosa et al., 2009) and involve in developmental process like embryogenesis to senescence’s (Franck et al.,2006;Knopp et al.,2006;Rolland et al., 2006;Geromel et al.,2008;Baliza et al.,2014). Chaves et al. (2017) reported the soluble sugars like starch (6.5 to 12.50 mmol kg-1 FW), sucrose (4 to 7 mmol kg-1 FW), and hexoses (3 to 10 mmol kg-1 FW) in seven years old of 2- meter-tall coffee trees. Jouve et al. (1993) reported total soluble sugars in arabica and canephora coffees at different storage temperatures.

    Impact of abiotic stress in coffee plant metabolism

    During abiotic stress, the plants face the problems from environmental factors as discussed above, problems arise in plant cell metabolisms in a sequential manner to deplete the plant by producing the more ROS, decreasing the photosynthesis and reduced the production of soluble sugars, finally, the plant will die. Reactive oxygen species may react with the long chains of amino acid residues, Cholesterol and triglycerides and genetic materials (DNA and RNA), causing oxidative damage and impairing the normal functions of cells (Foyer & Fletcher, 2001). The important source for ROS is chloroplast because in thylakoid membranes the excited pigments may interact with O2 to form strong oxidants such as O−2 or O12 (Niyogi, 1999). The electron transport chains of Photosystem-I (PSI) and photosystem-II (PS-II) are the major sources of ROS production and it is enhanced by conditions of limiting CO2 fixation, during stress condition in the electron transport chain supplying of NADP decreased, that leakage of electrons occurs from ferredoxin to oxygen (O2), reducing it to O2•− (Elstner, 1991; Asada, 2006; Siamsa et al., 2010;Shapiguzov et al., 2012;Sharma et al., 2012). This leakage of electrons to oxygen (O2) may also happen from 2Fe-2S and 4Fe-4S clusters in the electron transport chain (ETC) of Photosynthesis-I (PS-I). Whereas in PS-II, the acceptor side of the electron transport chain has QA and QB. The production of O2•− occurs from the leakage of electrons from QA and QB site to O2, formation of this O2•− by O2 is a rate-limiting step.

    In plants, the electron transport chain and ATP syntheses are tightly associated under ordinary aerobic conditions. Nevertheless, various stress factors lead to obstruction and modification of its components. Leading to over-demotion of electron carries at the low level production of ROS (Noctor et al., 2007;Blokhina & Fagerstedt, 2010;Siamsa et al., 2010). These have been implicated as secondary messengers in plant cells, including stomatal closure, programmed cell death, gravitropism (Jung et al., 2001;Mittler, 2002;Neill et al., 2002;Kwak et al., 2003;Yan et al., 2007).

    Superoxide dismutase (SOD, 1.15.1.1) will play a major role in all aerobic organisms. This enzyme belongs to the group of metalloenzymes and catalyzes the dismutation of O2•− into oxygen (O2) and hydrogen peroxide (H2O2). Three isozymes of SODs (Cu/Zn SOD), manganese superoxide dismutase and ferrous superoxide dismutase are announced in plants cells. All configurations of superoxide dismutase are nuclear-encoded for targeting to their particular subcellular compartments by an amino-terminal targeting sequence (Bowler et al., 1992;Racchi et al., 2001).

    O 2 · O 2 + H 2 O 2

    The first enzyme that is catalase (CAT, 1.11.1.6) was discovered and characterized. The tetrameric heme-containing catalase involves into the dismutation of two molecules of hydrogen peroxide into H2O and O2 (Del Río et al., 2006). Based on the expression pattern of the tobacco genes, catalase enzyme was classified in to three classes. Class-I catalases are expressed in photosynthetic tissues and regulated by light. Class-II catalases are expressed at greater levels in vascular tissues, although seed and young seedlings contain more about class-III catalase enzymes (Willekens et al., 1995).

    H 2 O 2 2 H 2 O + O 2

    Glutathione peroxidase (GPX, EC 1.11.1.7) enzyme contains four conserved disulfide bridges and two structural Ca2+ ions. Many isozymes of GPX are encoded by different genes and appeared in the cytosol, cell wall, and vacuoles. They can play a crucial role at formation and accumulation of lignin (lignification) in the cell wall, breakdown (degradation) of IAA, biosynthesis of ethylene, wound healing, and defense against biotic & abiotic stresses (Kobayashi et al., 1996).

    Ramalho et al. (2018) studied about antioxidative enzyme activities in three coffee species under drought and cold stress plants. High SOD activity was found in ‘Obata’ (2,800 units g-1 DW), ‘Icatu’ (4,300 units g-1 DW) and ‘Apaota’ (2,500 units g-1 DW). Catalase activity was appeared in ‘Obata’ (710 μmol H2O2 g-1 DW min-1), ‘Icatu’ (240 μmol H2O2 g-1 DW min-1) and ‘Apaota’ (170 μmol H2O2 g-1 DW min-1). Authors reported APX activity in ‘Obata’ (0.9 nmole ASC g-1 DW min-1), ‘Icatu’ (22 nmole ASC g-1 DW min-1) and ‘Apaota’ (10.3 nmole ASC g-1 DW min-1) and GR activity in ‘Obata’ (0.8 nmol NADPH g-1 min-1 DW), ‘Icatu’ (18 nmol NADPH g-1 DW min-1) and ‘Apaota’ (15 nmol NADPH g-1 DW min-1).

    The Impact of biotic stress on coffee plants

    In biotic stress, damage occurs by other living organisms, like bacteria, viruses, fungi, parasites, insects, weeds and cultivated or native plants. These agents consume the nutrients from the host and eventually reduce the plant vigor and in extreme cases, host plants get to die. When plants get affected continuously to biotic stress, causes changes of plant metabolism. Finally, physiological damages cause the less productivity. To overcome this problem, plants have developed an advanced protection mechanism. Thus, perception of plant protection mechanisms might stop the important crop and economic losses (Single & Krattinger, 2016; Gimenez et al., 2018). The problem which will occur by biotic stress is very critical to find immediately than abiotic stress. Whereas biotic stress is a little bit difficult to find the causative agent. But abiotic stress based on the symptoms can be identified easily than biotic stress.

    Major fungal diseases in coffee plants are anthracnose (Colletotrichum gloeosporioides, C. kahawae), armillaria root rot (Armillaria mellea), brown eye spot (Cercospora coffeicola), coffee berry disease (CBD) (C. kahawae), Bark disease (Fusarium stilboides), berry blotch (C. coffeicola), red blister disease (C. coffeicola), coffee leaf rust (CLR, orange or leaf rust) (Hemileia vastatrix), coffee wilt disease (CWD), Gibberella xylarioides (Fusarium xylarioides). Among all of these fungal diseases CLR, CBD, and CWD, Gibberella xylarioides (F. xylarioides) diseases are majorly playing a role to decrease the coffee crop yield (Hindorf et al., 2011). Nematodes and parasitic disease is root-knot disease caused by Meloidogyne spp. Due to this biotic stress, the significant threat happens to agriculture and food security (Roberts, 2013). Due to the turmoil of environmental change, the plant tends to increased susceptibility to pathogens. Additionally, abiotic stress factors also damaging the plants, so that plants getting susceptibility to pathogenes (Garrett et al., 2006). By chewing the leaf by insects reduce the leaf area so that photosynthesis rate will be decreased and some vascular-wilt and fungi eradicate the water transport. Hence photosynthesis may be decreased by inducing stomatal closure (Flexas et al., 2012).

    Effect of environmental change on coffee production

    Due to global warming, agriculture related mitigations (production system and plant management) and agronomical adaptation (breeding programs) strategies may have different in the world (Camargo et al., 2010). Coffee cultivation is fraught with hazards of climate change, labor scarcity and global currency fluctuation. Some low scale production farmers are getting most trouble in cash flow issues which affect their capability to conduct timely cultivation. After harvesting the coffee crop, processing of the fruit till the beans stage is linked with economy. Hence, the coffee plantation sector requires support and small growers cannot be expected to cope with challenges such as global currency fluctuations. These growers, therefore, have to be supported through the mechanism of minimum support price and generous subsidies. To overcome the global warming problem, we need to produce the coffee plants by implementing the new agronomic techniques and genetic engineering methods to produce a good yield and quality of coffee crops. Those agronomical techniques include planting at more thickness, vegetated soil, irrigation and genetically breeding (Bergo et al., 2008). We can produce the high quality coffee beans by different adaptations and mitigation practices which include, using of medium shade crops or covering materials, re-construct the forest, genetic improvement and intercropping of coffee-banana plants and so on. Different conservation practices such as covering with grass species and secondary products of crops, which successfully supply both nutrients, and retains humidity of soil, thus decrease the water evaporation. Medium shade crops planting in the above-mentioned manner also improve soil water availability, nutrient enrichment and serve as a medium shade tree (Perfecto & Armbrecht, 2003; GACSA, 2015; Abraham et al., 2017). By digging the terraces, storing and preserving the rain water for future uses is one of the best method to increase the water potential (Lin, 2008; Kimemia, 2014).

    Biotechnological aspects in improving the coffee production

    Biotechnology is the science which deals the practical applications of biological organisms or their internal sub cellular compounds in agriculture, medical field, various agriculture industries and environmental management (Kasonta et al., 2002). To overcome the environmental challenges like abiotic stress and biotic stress, producing plants by using a biotechnological approach like molecular biology, genetic engineering, and plant tissue culture technology is most important (Carneiro et al., 1997;Ben miflin, 2000;Santana-Buzzy et al., 2007). Plant breeders use the technic to create a superior variety by taking genetic polymorphic plants with in each crop, and finally make them a huge quantity for economic purpose. Traditional breeders use classical genetic principles. This approach will take many years to incorporate desirable traits into crop varieties. Each parental line donates half of the genetic material to the progeny by traditional breeding. After several generations, the resulted unfavorable traits have to be exhausted. The progeny has to be tested in each generation to confirm the desired traits (Fazuoli et al., 2000;Ashebre, 2016;Banavath et al., 2018). This type of breeding aspect will take the long process, highly expensive, time taken and has to wait for many generations to get the desired traits. By using Modern agricultural biotechnological tools, the breeders can manipulate the genetic make-up of organisms and processing of agricultural products. Till now some transgenic coffee plants were developed to overcome the abiotic and biotic stress. Some of the genes which were transformed in the coffee plants are discussed below and the genes, promoters, reporter genes and explants for the study were shown in Table 1.

    Abiotic tolerance genes in coffee

    The C. canephora dehydration responsive element binding transcription factor (CcDREB1D) is a promoter, belongs to the dehydration responsive element binding (DREB) transcription factor family that involve majorly in controlling the expression of genes under abiotic and biotic stress. The transgenic C. arabica carrying this promoter showed tolerance to abiotic stress (water deficit) (Torres et al. 2016). DREB1D promoter haplotypes (HP15, HP16, and HP17) was shown the tolerance against abiotic stress (cold and water deficit) in C. arabica by regulating elements of this promoter involved in ABA-dependent, independent network, tissue specificity and in light regulations (Alves et al., 2017).

    Biotic stress tolerance genes in coffee

    Cry1Ac gene was isolated from Bacillus thuringiensis and it is one of the delta-endotoxins which act as insecticide. Cry 1Ac gene was transformed in C. canephora and C. arabica to protect from the pest that is the coffee leaf miner (Perileucoptera coffeella and Leucoptera spp.) (Leroy et al., 1999).

    The WRKY1 (CaWRKY1) gene presented in C. arabica shows the tolerance against abiotic and biotic stress (Rust fungus Hemileia vastatrix). This gene contains CaWRKY1a and CaWRKY1b of two homologous genes identified in C. arabica allotetraploid genome (Anne et al., 2013). α-amylase inhibitor -1 gene (α-AI1) also protects the coffee plants from coffee berry borer insect-pest by Hypotheneumus hampei (Barbosa et al., 2010;Erika et al., 2015).

    The bar reporter gene was cloned from Streptomyces bacteria this organism can produce the tri peptide bialaphos as a secondary metabolite. The bar gene has been used to engineer herbicide resistant plants. Cunha et al. (2004), Cruz et al. (2004) and Ribas et al. (2005) were cloned this bar gene in coffee plant tolerance to herbicide ammonium glufosinate.

    β-glucuronidase (GUS) useful in the plant molecular biology system as a reporter gene. It can use for the identification and screening of transgenic coffee plants (Spiral & Petiard, 1991;Van Boxtel et al., 1995;Da silva & Yuffa, 2003;Rosillo et al., 2003).

    Red fluorescent protein was taken from the coral Discosoma striata (DsRFP) and this gene was cloned in the coffee plant by Agrobacterium-mediated transformation. Red fluorescent protein was act as a reporter gene in the coffee plant (Canche-Moo et al., 2006). Hygromycin phosphotransferase (HptII) and rolA gene was transformed in C. canephora plants by A. rhizogenes (Vinod Kumar et al., 2006).

    Some biotic stress tolerance genes are present in coffee plants. Those genes are cloned and characterization was done. C. arabica nonexpressor of pathogenesis-related gene 1 called CaNPR1. This gene played a major role in fungal diseases like coffee leaf rust caused by H. vastatrix. This nonexpressor of pathogenesis-related (NPR1) gene was shown homology in other crops (Cavallari et al., 2013), and it may play a wide role on biotic and abiotic stress tolerance in other crops (Silva et al., 2018).

    Some genes in coffee plants will play role on biotic stress those genes are like GAPDH (SGN-U 347734, SGN-U 356404, 60S RPL7 and SGN-U351477), ADH (SGN-U 350348), UBQ (SGN-U 347154) and actin 7 plays role on diseases caused by H. vastatrix (Barsalobres- Cavallari et al., 2009;Joseph et al., 2018).

    Some of the reference genes which are present in coffee plant tissues, expression studies were done from C. arabica (12 genes) and from C. canephora (8 genes). Those genes are ubiquitin (UBQ), Clathrin adaptor protein medium subunit (AP47), 60S ribosomal protein L39 (RPL39), elongation factor 1α (EF1α), class III alcohol dehydrogenase (ADH2), β-actin (ACT), glyceraldehyde 3- phosphate dehydrogenase (GAPDH), 24S (Ribosomal protein 24S), UBQ10, β-tubulin (TUB), Photosystem I P700 chlorophyll an Apo protein A2 (PSAB), caffeine synthase (DXMT), MDH and protein phosphatase 2A (PP2A) (Fernandes- Brum et al., 2017). Cavallari et al. (2009) was suggested that some internal control genes be useful for expression studies in C. arabica under different experimental conditions. Those genes are 60S ribosomal protein L7 (RPL7), ADH, 14-3-3, poly ubiquitin, β-actin and glyceraldehyde- 3-phosphate dehydrogenase. Cruz et al. (2009) also observed gene relative expression studies in coffee plants grown under abiotic stress conditions. Those genes are PsaB, PP2A, AP47, S24 (ribosomal protein), GAPDH, large ribosomal subunit 39 (rpl39), polyubiquitin 10 (UBQ10), ubiquitin-like protein (UBI9). Theobromine was a major intermediate product during the caffeine biosynthesis. This compound was studied with CaXMT1, CaMXMT1, CaMXMT2 and CaDXMT1 genes in coffee plants (Ogita et al., 2004). To understand the drought tolerance during the water deficit conditions, total 38 gene expression studies were done in two commercial cultivars (C. arabica cv. ‘IAPAR59’ and ‘IAPAR59’) (Mofatto et al., 2016). Similarly, to understand the light regulation mechanism in plants ribulose 1,5 bisphosphate carboxylase/oxygenase (RBCS1) promoter demonstrated as a leaf-specific and light-regulated promoter in tobacco plants (Marraccini et al., 2003).

    The non-specific lipid transfer proteins (nsLTP) sequence was isolated from C. arabica and C. canephora for clone in tobacco plants to study the functional characterizations and genomic analysis (Cotta et al., 2014). The fulllength C. arabica domain-containing protein (CaBDP) gene sequence was extracted from RNA of drought-stressed C. arabica leaves. The gene was cloned in Arabidopsis to characterize the drought and salt tolerance in plants (Nguyen et al., 2016;Nguyen & Hunseung, 2017). Metallothionine proteins including CaMT4, CaMT15, CaMT3, and CaMT8 gene expression studies were done by treating the high and less copper (Cu) and zinc (Zn) nutrient solution to C. arabica plants, Main aim of this investigation was to study the role of metallothionine in the maintenance of Cu and Zn homeostasis and in detoxification of excessive levels of these nutrients (Bulgarelli et al., 2016).

    Caffeine synthesis takes place by the action of xanthosine through N-methylation of C. arabica xanthosine methyltransferase 1 (CaXMT1), CaMXMT2, and CaDXMT1 genes (Uefuji et al., 2003). The coding for the 11Sglobulin seed storage protein (CSP1) of coffee gene was cloned in tobacco and promoter analysis and characterization was done (Marraccini et al., 1999). The coffee translation initiation factor Full name CaSUI1 gene was extracted from arabica beans during maturation and cloned for expression analysis finally observed the similarities with rice, maize and yeast SUI1 gene (Charlotte et al., 2003). During the drought conditions, the C. arabica homeobox 12 (CAHB12) gene was isolated from coffee for investigating the homeobox genes in the coffee genome project. Phylogenetic analysis (maximum likelihood method) described this CAHB12 gene is belongs to the Full name HD-ZIPL family and the expression pattern of CAHB12 gene in leaves and coffee roots was analyzed by real-time PCR (Priscilla et al., 2016).

    Importance of coffee in medicine and health issues

    Coffee contains 800 phenolic compounds are produced as secondary metabolites with aromatic rings, these compounds protect the plants from external environments (Monteiro et al., 2012). Alkaloids, terpenoids, carotenoids and some other enzymes are commonly present in coffee. Some important compounds like caffeic derivatives of poly phenols, p-coumaric derivative of cinnamic acid, vanillic, ferulic, and protocatechuic acid (Act on anti-inflammatory, anti tumoral, antispasmodica etc) are present in all coffee taxa (Stalikas et al., 2007). Moreover, beans contain 5-caffeoylquinic acid (5-CQA), feruloylquinic acids (3-, 4- and 5-FQA), the isomers of monoester, diester caffeoylquinic acids, various iridoid glycosides, dioxoanthracene (anthraquinonoids) and tannins (Mondolot et al. 2006;Wiart et al. 2006) are present. It's having so many medical importance’s for human beings to reduce the disease causative agents. It will decrease the ROS by increase the antioxidants in human body for the fight against which will involve in cellular damage to the heart diseases and some cancers (Ramalakshmi et al. 2008). Coffee reduces the feasibility of cancers of kidney, liver, premenopausal breast, and colon by the presence of caffeine, diterpenoid, caffeic acid, polyphenols, essential oil content, and heterocyclic molecules (Nkondjock, 2009). It will play a major role in gastrointestinal, dermatological, cardiovascular, nervous system and it will stimulate the respiratory system. It’s having antiviral, antifungal, antibacterial, anti-cellulitic, anti-aging, inflammatory and anti-allergic activity (Narayana et al., 2001;Boros et al., 2010;Kiran et al., 2011;Patay et al., 2016). The coffee fruit, leaf sap, flowers, and root saps were using for the treatment of the different types of diseases in many countries (Ghimire et al., 2009;Patay et al., 2016).

    CONCLUSION

    We have reviewed the effects of biotic, abiotic stress and crop management on the composition of coffee and the essential implications for quality and production. Coffee has a sufficient supply of instant energy so that the bean contains sufficient, good quality proteins and medicinal values. One aspect, in particular, that needs much more investigation to identify of various environmental stresses that affect coffee production and implicate for food safety. We also explained how these stresses interact with genetic factors and will be affected by climate change. This review explained the better understanding of the defense mechanism against oxidative stress. Most of the area cultivated coffee plants are attacked by different pathogens; hence more precautions have to be taken for coffee crop protection. Explained in detail climate change effects on coffee production and advantages of biotechnological aspects include molecular biology and genetic engineering aspects to improve the crop productivity.

    적 요

    커피(Coffea L.)는 꼭두서니과에 속하는 열대지역 농가의 대 표적인 경제작물로서 많은 단백질(25–28%)과 의학적 가치를 가지고 있다. 커피는 환경에 민감한 작물로서 기후변화는 커 피의 품질과 안정적 생산에 중대한 영향을 미친다. 커피에서 저항성 반응에 대한 비생물학적 baroreceptor를 개발하기 위해 다양한 생육단계, 그리고 여러가지 스트레스 조건하에서 생산 성을 높이기 위한 많은 연구가 이루지지고 있다. 다양한 생리 학적, 생태학적 및 생화학적 파라미터들은 커피의 생산성과 품 질을 변화시킨다. 이 논문은 커피에서 중요한 생물학적 및 비 생물학적 저항성에 대한 고찰을 실시하였다. 또한 커피의 생 산성 향상을 위한 최선의 이행방법과 약리학적인 가치, 그리 고 작물개량을 위한 생명공학적 접근방법을 제시하였다.

    ACKNOWLEDGMENTS

    This study was supported by 2019 the RDA Fellowship Program (Project No : PJ013879012019) of National Institute of Horticultural and Herbal Science (NIHHS), Rural Development Administration (RDA), Republic of Korea.

    Figure

    KSIA-31-4-359_F1.gif

    Cellular events and signaling mechanism under stress condition in plant cell.

    KSIA-31-4-359_F2.gif

    Outline of the general response on drought, salt and high temperature stress in plants.

    Table

    Studies on coffee genetic transformation

    Reference

    1. Abraham, A , and D. Ebisa.2017. Climate Smart Coffee (C. arabica) Production. Americ. Data Min. Kanowl. Disc. 2(2): 62-68.
    2. Adugna, A. , C.S. Paul.2011. Effects of shade on growth, production and quality of coffee (Coffea arabica) in Ethiopia. J. Hortic. For. 3(11): 336-341.
    3. Almeida A-AF. , M. Maestri.1997. Photosynthetic oxygen evolution by four Coffea arabica genotypes subjected to a dehydration/ rehydration cycle. J. Hort. Sci. 72: 593-599.
    4. Alpizar, E. , E. Dechamp, B. Bertrand, P. Lashermes, and H. Etienne.2006. Transgenic roots for functional genomics of coffee resistance genes to root-knot nematodes, in Proceedings of the 21st International Conference on Coffee Science (ASIC ’06), pp. 653–659, Montpellier, France.
    5. Alves, G.S.C., L.F. Torres, E. Dechamp, J.C. Breitle, T. Joet, F. Gatineau, A.C. Andrade, B. Bertrand, P. Marraccini, andH. Etienne.2017. Differential fine-tuning of gene expression regulation in coffee leaves by CcDREB1D promoter haplotypes under water deficit. J. Exp. Bot. 68(11): 3017-3031.
    6. Anne, S.P. , C.B. Cavallari, D. Ramiro, A. Freire, H. Etienne, and D. Fernandez.2012. Promoter analysis of the WRKY transcription factors CaWRKY1a and CaWRKY1b homoeologous genes in coffee (Coffea arabica). Plant cell Rep. 32(8): 1263-76.
    7. Araujo, W.L. , P.C. Dias, G.A. Moraes, E.F. Celin, R.L. Cunha, R.S. Barros, and F.M. Da Matta.2008. Limitations to photosynthesis in coffee leaves from different canopy positions. Plant Physiol. Biochem. 46(10): 884-890.
    8. Arroyo-Herrera, A. , A. Ku Gonzalez, and R. Canche Moo.2008. Expression of WUSCHEL in Coffea canephora causes ectopic morphogenesis and increases somatic embryogenesis”. Plant Cell Tiss. Org. 94(2): 171-180.
    9. Asada, K. 1999. The water-water cycle in chloroplasts: scavenging of active oxygen’s and dissipation of excess photons.” Annul. Rev. Plant Biol. 50(1): 601-639.
    10. Ashebre, K.M. 2016. The Role of Biotechnology on Coffee Plant Propagation: A current topics paper. J. Biol. Agricul. healthcare. 6(5): 13-19.
    11. Ashraf, M. and M. R. Foolad.2007. Roles of glycine betaine and proline in improving plant abiotic stress resistance. Environ. Exp. Bot. 59(2): 206-216.
    12. Bajji, M. , J. M. Kinet, and S. Lutts.2002. Osmotic and ionic effects of NaCl on germination, early seedling growth and ion content of Atriplex halimus (Chenopodiaceae). Can. J. Bot. 80(3): 297-304.
    13. Baliza, D. P. , M.O. Santos, J.D. Alves, R.J. Guimarães, and R.L. Cunha.2014. Sucrose metabolism in coffee submitted to different shade levels. Coffee Science. 9(4): 445-455.
    14. Banavath, J.N. , T. Chakradhar, V. Pandit, S. Konduru, K.K. Guduru, C.S. Akhila, S. Podha, and C.O.R. Puli.2018. Stress Inducible Overexpression of AtHDG11 leads to Improved drought and salt stress tolerance in peanut (Arachis hypogaea L.). Front. Chem. 6: 1-34.
    15. Barbosa, A. E. , E.V.S. Albuquerque, M.C.M. Silva, D.S.L. Souza, O.B. Oliveira-Neto, R.T.L. Arnubio Valencia, and M.F. Grossi.2010. α -Amylase inhibitor-1 gene from Phaseolus vulgaris expressed in Coffea arabica plants inhibitsα-amylases from the coffee berry borer pest. BMC Biotechnol. 10: 44.
    16. Barros, R.S. , M. Maestri, and A.B. Rena.1999. Physiology of growth and production of the coffee tree - a review. J. Coffee Res. 27: 1-54.
    17. Barwick, M. and V.D.S. Anton.2004. Tropical and Subtropical Trees - A Worldwide Encyclopaedic Guide.Publisher.Thames & Hudson, London. ISBN-0-500-51181-0.
    18. Ben, M. 2000. Crop improvement in the 21st Century. J. Exp. Bot. 51(342): 1-8.
    19. Bergo, C.L. , R.C.A. Pereira, and F. Sales.2008. Avalia de genotipos de cafeeiros arabica e robusta no estado do Acre. Ciencia Agrotec., Lavras. 32(1): 11-16.
    20. Biruk, A. 2018. Impact of shade on morpho-physiological characteristics of coffee plants, their pests and diseases: A review. Afr. J. Agric. Res. 13(39): 2016-2014.
    21. Blokhina, O. and K.V. Fagerstedt.2010. Reactive oxygen species and nitric oxide in plant mitochondria: origin and redundant regulatory systems. Physiol. Planta.138(4): 447-462.
    22. Blum, A. and A. Ebercon.1981. Cell membrane stability as a measure of drought and heat tolerance in wheat. Crop Sci. 21(1): 43-47.
    23. Boreux, V. , P. Vaast, L.P. Madappa, K.G. Cheppudira, C. Garcia, and J. Ghazoul.2016. Agroforestry coffee production increased by native shade trees, irrigation, and liming. Agron. Sustain Dev. 36(3): 42.
    24. Boros, B. , S. Jakabov´a, A. D¨ornyei, G. Horv´ath, Z. Pluh´ar, and F. Kill´ar.2010. Determination of polyphenolic compounds by liquid chromatography-mass spectrometry in Thymus species. J. Chromatogr. A. 1217(51): 7972-7980.
    25. Bote, A.D. and P.C. Struik.2011. Effects of shade on growth, production and quality of coffee (Coffea arabica) in Ethiopia. J. Hortic. For. 3(11): 336-341.
    26. Bote, A.D. , Z. Zana, F.L. Ocho, and J. Vos.2018. Analysis of coffee (Coffea arabica L.) performance in relation to radiation level and rate of nitrogen supply II. Uptake and distribution of nitrogen, leaf photosynthesis and first bean yields. Euro. J. Agron. 92: 115-122.
    27. Bowler, C. , M. Van Montagu, and D. Inzé.1992. Superoxide dismutase and stress tolerance. Annu. Rev. Plant Physiol. Plant Mol. Biol. 43(1): 83-116.
    28. Bulgarelli, R. G. , P. Araujo, T. Tezotto, P. Mazzafera, and S.A.L. Andrade.2016. Expression of metallothionein genes in coffee leaves in response to the absence or excess of Cu and Zn. Theor. Exp. Plant Physiol. 28(4): 1-13.
    29. Burkhardt, J. , T. Kufa, A. Beining, H. Goldbach, and M. Fetene.2006. Different drought adaptation strategies of Coffea arabica populations along rainfall gradient in Ethiopia. Proceedings of the 21st International Conference on Coffee Science Colloquium, Sept. 11-15, Montpellier, France, pp: 1032-1036.
    30. Camargo, A.P. 1985. O clima e a cafeicultura no Brasil. Inf. Agropec. 11(126): 13-26.
    31. Camargo, M.B.P. 2010. The impact of climatic variability and climate change on arabic coffee crop in Brazil. Bragantia Campinas. 69(1): 1239-247.
    32. Campos, P.S , V. Quartin, J.C. Ramalho, and M. Antonieta Nunes.2003. Electrolyte leakage and lipid degradation account for cold sensitivity in leaves of Coffea sp. Plants. J. Plant Physiol. 160(3): 283 -292.
    33. Campostrini, E. and M. Maestri.1998. Photosynthetic potential of five genotypes of Coffea canephora Pierre. Rev. Bras. Fisiol. Veg. 10: 13-18.
    34. Canche-Moo, R.L. R. , A.K. Gonzalez, C. Burgeff, V.M.L. Vargas, L.C. Rodriguez-Zapata, and E. Castano.2006. Genetic transformation of Coffea canephora by vacuum infiltration. Plant Cell Tiss. Org. 84(3): 373-377.
    35. Cannell, M.G. 1985. Physiology of the coffee crop. In: Clifford MN, Willson KC (eds), Coffee - Botany, Biochemistry and Production of Beans and Beverage, pp.108-134. Crom Helm, London.
    36. Camargo, M.B.P. 2009. The impact of climatic variability in coffee crop. Artigo em Hypertexto. Disponvelem: <http://www.infobibos.com/Artigos/2009_2/ClimaticVariability/index.htm>.Acesso em:
    37. Carneiro, M.F. 1997. Coffee biotechnology and its applications in genetic transformation. Euphytica. 96(1): 167-172.
    38. Casper, B.B. , I.N. Forseth, H. Kempenich, S. Seltzer, and K. Xavier.2001. Drought prolongs leaf life span in the herbaceous desert perennial Cryptantha flava. Funct. Ecol. 15(6): 740-747.
    39. Cavallari, B. , C.F. Petitot, A.S. Severino, F.E. Maia, and D. Fernandez.2013. In Microbial Pathogens and Strategies for Combating Them: Science, Technology and Education. 1- 774 (ed A. Mendez-Vilas) (Formatex Research Center, Badajoz).
    40. Cavallari, F.B. , F.B. Severino, M.P. Maluf, and I.G. Maia.2009. Identification of suitable internal control genes for expression studies in Coffea arabica under different experimental conditions. BMC Mol. Biol. 10(1): 1-11.
    41. Charlotte, G. , C. Victoria, D. Alain, and M. Pierre.2003. Molecular cloning of a full-length cDNA and gene from Coffea arabica encoding a protein homologous to the yeast translation initiation factor SUI1: expression analysis in plant organs. Braz. J. Plant Physiol. 15(1): 55-58.
    42. Chastain, D.R. , J.L. Snider, G.D. Collins, C.D. Perry, J. Whitaker, and S.A. Byrd.2014. Water deficit infield-grown Gossypium hirsutum, primarily limits net photosynthesis by decreasing stomatal conductance, increasing photorespiration, and increasing the ratio of dark respiration to gross photosynthesis. J. Plant Physiol. 171(17): 1576-1585.
    43. Chaves, A.R.M. , A. Ten-Caten, H.A. Pinheiro, A. Ribeiro, and F.M. DaMatta.2008. ‘Seasonal changes in photo protective mechanisms of leaves from shaded and unshaded field-grown coffee (Coffea Arabica L.) trees. Trees. 22(3): 351-361.
    44. Chaves, A.R.M.,S.C.V. Martin, K.D. Batista, E.F. Celin, and F.M.Da Matta.2012. Varying leaf-to fruit ratio affect branch growth and dieback, with little to no effect on photosynthesis, carbohydrates (or) mineral pools, in different canopy positions of field-grown coffee trees. Environ. Exp. Bot. 77(2012): 207-218.
    45. Chiang, H.H. and A.M. Dandekar.1995. Regulation of proline accumulation in Arabidopsis thaliana (L) Heynh during development and in response to desiccation. Plant Cell. Environ. 18(11): 1280-1290.
    46. Cotta, M.G., L.M. Barros, J.D. de Almeida, F. de lamotte, E. Barbosa, G.S. Vieira N, Costa Alves GS, Vinecky F, A.C. Andrade, and P. Marraccini.2014. Lipid transfer proteins in coffee: isolation of Coffea orthologs, Coffea Arabica homeologs, expression during coffee fruit development and promoter analysis in transgenic tobacco plants. Plant Mol. Biol. 85(1-2): 11-31.
    47. Cruz, A.R.R. , A.L.D. Paixão, F.R. Machado, M.F.F. Barbosa, C.S. Junqueira, G.B. Cabral, J.B. Teixeira, A.K. Kobayashi, A.C.M. Brasileiro, and E.V.S.A. Barros.2004. Metodologia para obtencao de plantas transformadas de Coffea canephora por co-cultivo de calos embriogenicos com A. tumefaciens. Boletim de Pesquisa e Desenvolvimento 58. Embrapa, Brasilia 15p
    48. Cruz, F. , K. Samara, N. Paula, C. Carlos, A. Juliana, B. Leila, R. Eduardo, F.G.S. Maria, F.S.V. Maite, and A.F. Marcio.2009. Evalation of coffee reference genes for relative expression studies by quantitative real-time RT-PCR. Mol. Breeding. 23(4): 607-616.
    49. Cunha, W.G. , F.R.B. Machado, G.R. Vianna, J.B. Teixeira, and E.V.S.A. Barros.2004. Obtencao de Coffea arábica geneticamente modificadas por bombardeamento de calos embriogenicos. Boletim de Pesquisa e desenvolvimento 73. Embrapa, Brasilia. 73: 15.
    50. Da Silva, R.F. and A.M. Yuffá.2003. Transient gene expression in secondary somatic embryos from coffee tissues electroporated with the genes GUS and BAR. Electronic J. Biotech. 6(1): 629-635.
    51. Da Matta, F.M. , M. Maestri, R.S. Barros, and A.J. Regazzi.1993. Water relations of coffee leaves (Coffee arabica and C. canephora) in response to drought. J. Hort. Sci. 68(5): 741-746.
    52. Da Matta, F.M. , J.S.M. Silveira, C. Ducatti, and M.E. Loureiro.2000. Eficiencia do uso da agua e tolerancia a seca em Coffea canephora. In: Expanded Abstracts of the I Simposio de Pesquisa dos Cafes do Brasil. Embrapa Cafe, Brasilia pp. 907-910.
    53. Da Matta, F.M. 2004. Ecophysiological constraints on the production of shaded and unshaded coffee. Review. Field crops Res. 86(2-3): 99-114.
    54. Da Matta, F.M. and J.D.C. Ramalho.2006. Impacts of drought and temperature stress on coffee physiology and production. Braz. J. Plant Physiol.18(1): 55-81.
    55. Da Matta, F.M. , M. Maestri, P.R. Mosquim, and R.S. Barros.1997. Photosynthesis in coffee (Coffee Arabica and C.canephora) as effected by winter and summer conditions. Plant science. 128: 43-50
    56. Da Matta, F.M. , C.P. Ronchi, M. Maestri, and R.S. Barros.2008. Ecophysiology of coffee growth and production. Braz. J. Plant Physiol.19(4): 485-510
    57. Da Matta, F.M. and A.B. Rena.2001. Tolerancia do cafe a seca. In: Zambolin L (ed), Tecnologias de Producao de Cafe com Qualidade, pp.65-100. Universidade Federal de Vicosa, Vicosa
    58. Davis, A.P. , T.W. Gole, S. Baena, and J. Moat.2012. The Impact of Climate Change on Indigenous Arabica Coffee (Coffea arabica): Predicting Future Trends and Identifying Priorities. PLoSONE.7(11): e47981.
    59. De carvalho, K. , M.K.F. de Campos, D.S. Domingues, L.F.P. Pereira, and L.G.E. Vieira.2013. The accumulation of endogenous proline induces changes in gene expression of several antioxidant enzymes in leaves of transgenic Swingle citrumelo. Mol. Biol. Rep. 40(4): 3269-3279.
    60. De pena, M. 1995. Development of stable transformation procedure for the protoplasts of Coffea arabica cv. Columbia. Doctoral thesis. University of purdue P. 75.
    61. Del Río, L.A. , L.M. Sandalio, F.J. Corpas, J.M. Palma, and J.B. Barroso.2006. “Reactive oxygen species and reactive nitrogen species in peroxisomes. Production, scavenging, and role in cell signaling.” Plant Physiol. 141(2): 330-335.
    62. Des Marais, D.L. 2017. The influence of time on the drought response of Brassica rapa, an agriculturally important species of plant, has been clarified. Drought stress: in to the fourth dimension. ELife-6: e31328.
    63. Devasagayam, T.P. , J.P. Kamat, H. Mohan, and P.C. Kesavan.1996. Caffeine as an antioxidant: inhibition of lipid peroxidation induced by reactive oxygen species. Biochem. Biophys Acta. 1282(1): 63-70.
    64. Dias, P.C. , W.L. Araujo, G.A.B.K. Moraes, R.S. Barros, and F.M. Da Matta.2007. Morphological and physiological responses of two coffee progenies to soil water availability. J. Plant. Physiol. 164(12): 1639-1647.
    65. Dong, T.L. , D.I. Forrester, C. Beadle, R. Doyle, N.H. Hoang, N.X. Giap, and D. Worledge.2016. Effects of light availability on crown structure, biomass production, light absorption and light-use efficiency of Hopea odorata planted within gaps in Acacia hybrid plantations. Plant Ecol. Divers. 9(5-6): 1-14.
    66. Elstner, E. F. 1991. Mechanisms of oxygen activation in different compartments of plant cells,” in active oxygen/oxidative stress and plant metabolism, E. J. Pell and K. L. Steffen, Eds., 13-25. American Society of Plant Physiologists. Rockville, Md, USA.
    67. Erika, V.S.A. , A.B. Caroline, J.V. Romero, J.W.A. Valencia, A.V. Jimenez, L.M. Pimenta, A.E.A.D. Barbosa, M.C.M. Silva, A.M. Meneguim, M.E.L. Sa, G. Engler, J.A. Engler, D. Fernandez, and F.G.S. Maria.2015. Seed-specific stable expression of the α-AI1 inhibitor in coffee grains and the in vivo implications for the development of the coffee berry Borer. Trop. Plant Biol. 8(3-4): 98-107.
    68. Etienne, H. , P. Lashermes, A. Menendez-Yuffa, Z. de Guglielmo- Croquer, E. Alpizar and H.L. Sreenath.2008. “Coffee,” in Compendium of Transgenic Crop Plants, Transgenic Plantation Crops, Ornamentals and Turf Grasses, C. Kole and T.Hall, Eds., pp. 57-84, Wiley Blackwell Publishers, London, UK.
    69. Eveline, D. , B. Jean-Christophe, L. Thierry, and E. Hervé.2015. Coffee (Coffea arabica L.) Agrobacterium Protocols: Methods in Molecular Biology. 21224.
    70. Fabro, G. , I. Kovacs, V. Pavet, L. Szabados, and M.E. Alvarez.2004. Proline accumulation and AtP5CS2 gene activation are induced plant-pathogen incompatible interactions in Arabidopsis. Mol. Plant Microbe. Interact. 17(4): 343-350.
    71. Fanjul, L. , R.R. Arreola, and C.M. Mendez.1985. Stomatal responses to environmental variables in shade and sun-grown coffee plants in Mexico. Exp. Agricul. 21: 249-258.
    72. Farooq, M. , A. Wahid, N. Kobayashi, D. Fujita, and S.M.A. Basra.2009. Plant drought stress: effects, mechanisms and management. Agron. Sustain. Dev. 29(1): 185-212.
    73. Fazuoli, L.C. , M.P. Maluf, O.G. Filho, H.M. Filho, and M.B. Silvarolla.2000. Breeding and biotechnology of Coffee. P.27-45. In: T. Sera, C.R. Soccol, A. Pandey and S. Roussos (eds.), Coffee Biotechnology and Quality. Kluwer Academic Publishers, Netherlands.
    74. Fernandes, B.C.N. , G. Bruno de Oliveira, M. Rafael Oliveira, S. Solange Aparecida, B. Horllys Gomes, L. André Almeida, F. Natália Chagas, L. Renato Ribeiro de, C.S. Carlos Henrique, and C.J. Antonio.2017. A panel of the most suitable reference genes for RT-qPCR expression studies of coffee: screening their stability under different conditions. Tree Genet. Genomes. 13(6): 1-13.
    75. Fernandez-Da Silva, R. and A. Men´endez-Yuff´a.2003. Transient gene expression in secondary somatic embryos from coffee tissues electroporated with the genes GUS and BAR. Elect. J. Biotech. 6(1): 29-35.
    76. Flexas, J. , F. Loreto, and H. Medrano.2012. Terrestrial photosynthesis in a changing environment. A Molecular, Physiological, and Ecological Approach. CUP. ISBN 978-0-521-89941-3 (hardback)
    77. Foyer, C.H. 1997. “Oxygen metabolism and electron transport in photosynthesis,” in Molecular Biology of Free Radical Scavenging Systems. J. Scandalios, Ed., pp. 587-621, Cold Spring Harbor Laboratory Press, New York, NY, USA
    78. Foyer, C.H. and J. Harbinson.1994. “Oxygen metabolism and the regulation of photosynthetic electron transport,” in causes of photo oxidative stresses and amelioration of defense systems in plants, C. H. Foyer and P. Mullineaux, Eds., pp. 1-42, CRC Press, Boca Raton, Fla, USA.
    79. Foyer, C.H. and J.M. Fletcher.2001. Plant antioxidants: color me healthy. Biologist. 48(3): 115-120.
    80. Franck, N. , P. Vaast, J. Génard and M. Dauzat.2006. Soluble sugars mediate sink feedback down-regulation of leaf photosynthesis in field- grown Coffea arabica. Tree Physiol. 26(4): 517-525.
    81. Franco, C.M. 1958. Influence of temperature on growth of coffee plant. IBEC Research Institute. New York. Bulletin No 16.
    82. Friend, D.J. 1984. Shade adaptation of photosynthesis in Coffea arabica. J. Photosyn. Res. Netherlands 5(4): 325-334.
    83. Geromel, C. , L.P. Ferreira, F. Davrieux, B. Guyot, F. Ribeyre, M.B.S. Scholz, L.F.P. Pereira, P. Vaast, D. Pot, T. Leroy, A.A. Filho, L.G.E. Vieira, P. Mazzafera, and P. Marraccini.2008. Effects of shade on the development and sugar metabolism of coffee (Coffea arabica L.) fruits. Plant Physiol Biochem. 46(5-6): 569-579.
    84. Ghimire, K. and R. R. Bastakoti.2009. Ethnomedicinal knowledge and healthcare practices among the Tharus of Nawalparasi district in central Nepal. For. Ecol. Manag. 257(10): 2066-2072.
    85. Gimenez, E. , M. Salinas, and F.A. Manzano.2018. Worldwide research on plant defense against biotic stresses as improvement for sustainable agriculture. Review. Sustainability. 10(2): 1-19.
    86. Greenwood, D.C. , N.J. Thatcher, J. Ye, L. Garrard, G. Keogh, L.G. King, and J.E. Cade.2014. Caffeine intake during pregnancy and adverse birth outcomes: a systematic review and dose-response meta-analysis. Eur. J. Epidemiol. 29(10): 725 - 734.
    87. Grosso, L.M. and M.B. Bracken.2005. Caffeine metabolism, genetics, and perinatal outcomes: A review of exposure assessment considerations during Pregnancy. Ann. Epidemiol. 15(6): 460-466.
    88. Gulmon, S.L. and C.C. Chu.1981. The effects of light and nitrogen on photosynthesis, leaf characteristics, and dry matter allocation in the chaparral shrub, Diplacus aurantiacus. Stanford, California 94305, USA
    89. Haggar, J. and K. Schepp.2012. Coffee and climate change. Desk study: impacts of climate change in four pilot countries of the coffee and climate initiative. Hamburg: Coffee and Climate. Natural resources institute, climate change, agriculture and natural resources, university of Greenwich. 51 p
    90. Haile, M. and W.H. Kang.2018. Growth and physiological responses of coffee (Coffea arabica L.) seedlings irrigated with diluted deep sea water. Afri. J. Agri. Rese. 13(7): 311-320.
    91. Hayat, S. , Q. Hayat, M.N. Alyemeni, A.S. Wani, J. Pichtel, and A. Ahmad.2012. Role of proline under changing environments. Plant Signal. Behav. 7(11): 1456-1466.
    92. Hindorf, H. and C.O. Omondi.2011. A review of three major fungal diseases of Coffea arabica L. in the rainforests of Ethiopia and progress in breeding for resistance in Kenya. J. Adva. Res. 2(2): 109-120.
    93. Hiramoto, K. , X. Li, M. Makimoto, T. Kato, and K. Kikugawa.1998. Identification of hydroxyl hydroquinone in coffee as a generator of reactive oxygen species that break DNA single strands. Mutat Res.419(1-3): 43-51.
    94. Hoekstra, F. , E. Golovina, and J. Buitink.2001. Mechanisms of plant desiccation tolerance. Trends Plant Sci. 6(9): 431-438.
    95. Hogler, H. and O.O. Chrispine.2010. A Review of three major fungal diseases of Coffea arabica L. in the rainforests of Ethiopia and progress in breeding for resistance in Kenya. J. Adva. Res. 2(2): 109-120.
    96. Indu, E.P. 2004. Micro propagation, somatic embryogenesis and agrobacterium mediated transformation of Coffea canephora pierre ex froehner, Ph.D thesis, university of mysore. Karnataka, India.
    97. Istudor, V. 2005. Farmacognozie, fitochimie, fitoterapie, Vol. III. Bucures,ti: Editura Medical_a; 265-266.
    98. Joseph, J.T. , N.J. Poolakkalody, and J.M. Shah.2018. Plant reference genes for development and stress response studies. J. Biosci. 43(1): 73-187.
    99. Jouve, L. , F. Engekmann, N. Noirot, and A. Charrier.1993. Evolution of biochemical markers (sugar, proline, malonedialdehyde and ethylene) for cold sensitivity in micro cuttings of two coffee species. Plant science. 91(1): 109-116.
    100. Jung, H.J. , S.B. Yun, and S.L. June.2001. Role of auxininduced reactive oxygen species in root gravitropism. Plant Physiol. 126(3): 1055-1060.
    101. Kanechi, M. , N. Uchida, T. Yasuda, and T. Yamaguchi.1995. Water stress effects on leaf transpiration and photosynthesis of Coffea arabica L. under different irradiant conditions. Proceedings of the 16th International Scientific Colloquium on Coffee (ASIC), April 9-14, Kyoto, Japan, pp: 853-859.
    102. Kasonta, J.S. , A.E. Lyaruu, P.C. Chuwa, K.M. Hosea, and Y.M. Kohi (Eds).2002. Biotechnology research and development policy: The basis for socioeconomic development in Tanzania. Proceedings of three National Biotechnology Policy Workshops in Tanzania during 2001/2 within the Bio-Earn.Costech, Dar es Salaam, Tanzania. (www.costech.or.tz, cited on 25th July, 2011)
    103. Kimemia, J. 2014. Climate change and its mitigation in sustainable coffee production, Coffee research institute.
    104. Kiran, B. , R. Baruah, R. Ojha, V. Lalitha, and K.A. Raveesha.2011. Antibacterial and antioxidant activity of Coffea benghalensis Roxb. Ex. Schult. Fruit against human bacteria. Res. J. Pharm. Biol. Chem. Sci. 2(3): 856-865.
    105. Knopp, S. , Bytof, G. , and D. Selmar.2006. Influence of processing on the content of sugars in green Arabica coffee beans. Eur. Food Res. Technol. 223(2): 195-201.
    106. Kobayashi, K. , Y. Kumazawa, K. Miwa, and S. Yamanaka.1996. ε-(γ-Glutamyl) lysine cross-links of spore coat proteins and transglutaminase activity in Bacillus subtilis. FEMS Microbiol. Lett. 144(2-3): 157-160.
    107. Koch, K. 2004. Sugar metabolism: regulatory mechanisms and pivotal roles in sugar sensing and plant development. Curr. Opin. Plant Biol. 7(3): 235-246.
    108. Koch, K.E. 1996. Carbohydrate-modulated gene expression in plants. Annu. Rev. Plant Physiol. Plant Mol. Biol. 47(1): 509-540.
    109. Koyro, H.W. , P. Ahmad, and N. Geissler.2012. Abiotic stress responses in plants: An Overview. In: Ahmad P. and M. Prasad (eds) Environmental Adaptations and Stress Tolerance of Plants in the Era of Climate Change. Springer, New York, NY. https://doi.org/10.1007/978-1-4614-0815-4_1. ISBN: 978-1-4614-0814-7.
    110. Kramer, P.J. and J.S. Boyer.1995. Water relations of plants and soils. Academic Press. New York
    111. Kufa, T. and J. Burkhardt.2011. Stomatal characteristics in Arabica coffee germplasm accessions under contrasting environments at jimma, southwestern Ethiopia. Int. J. Bot. 7(1): 63-72
    112. Kumar, U. and K.J. Boote.2012. Chapter two - Effect of climate change factors on processes of crop growth and development and yield of groundnut (Arachis hypogaea L.). Advan. Agron. 116: 41-69.
    113. Kumar, D. and L.L Tieszen.1980. Photosynthesis in Coffea arabica. I. Effects of light and temperature. Experi. Agricul. 16(1): 13-19.
    114. Kwak, J.M. , I.C. Mori, and Z.M. Pei.2003. NADPH oxidase AtrbohD and AtrbohF genes function in ROS-dependent ABA signaling in Arabidopsis. EMBO Journal. 22(11): 2623-2633.
    115. Lashermes, P. , M.C. Combes, J. Robert, P. Trouslot, A. D’Hont, F. Anthony, and A. Charrier.1999. Molecular characterization and origin of the Coffea arabica L. genome. Mol. Gen. Genet. 261(2): 259-266.
    116. Laureano, R.G. , Y.O. Lazo, J.C. Linares, A. Luque, F. Martínez, J.I. Seco, and J. Merino.2008. The cost of stress resistance: construction and maintenance costs of leaves and roots in two populations of Quercus ilex. Tree physiol. 28(11): 1721-1728.
    117. Leroy, T. , A.M. Henry, M. Royer, R.F. Altosaar, D. Duris, and R. Philippe.2000. Genetically modified coffee plants expressing the Bacillus thuringiensis cry1Ac gene for resistance to leaf miner. Plant Cell Rep. 19(4): 382-389.
    118. Levitt, J. 1980. Responses of Plants to Environmental Stresses. Vol. II. Madison, WI: Academic Press. 1911: 129-186.
    119. Liu, X. , Y. Qi, F. Li, Q. Yang, and L. Yu.2018. Impacts of regulated deficit irrigation on yield, quality and water use efficiency of arabica coffee under different shading levels in dry and hot regions of southwest china. Agricul. Water Manage. 204(46): 292-300.
    120. Liu, M. , Z. Wang, S. Li, X. Lu, X. Wang, and X. Han.2017. Changes in specific leaf area of dominant plants in temperate grasslands along a 2500-km transect in northern china. Sci. Rep. 7(1): 1-9.
    121. Liu, X. , M. Wan, H. Wu, and Q. Yang.2016. Photosynthetic response and use of water and light arabica coffee leaf under different irrigation and light levels. Oxid. Commun. 39: 873-883.
    122. Maduraimuthu, M. and P.V. Vara Prasad.2014. High temperature stress, plant genetic resources and climate change. Publisher: CABI. Editors: M. Jackson, B.V. Ford-Lloyd, M.L. Perry, pp. 201-220.
    123. Mariga, D.S. , C.H. Ngugu, F. Tegla, and Loroupe.2016. A review on heat and drought tolerance in coffee. Adv. Agric. Agric. Sci. 2(8): 160-163.
    124. Marraccini, P. , C. Courjault, V. Caillet, F. Lausanne, B. Lepage, W. John Rogers, S. Tessereau, and A. Deshayes.2003. Rubisco small subunit of Coffea arabica: cDNA sequence, gene cloning and promoter analysis in transgenic tobacco plants. Plant Physiol. Biochem. 41(1): 17-25.
    125. Marraccini, P. , A. Deshayes, V. Vincent Pétiard, and W.J. Rogers.1999. Molecular cloning of the complete 11S seed storage protein gene of Coffea arabica and promoter analysis in transgenic tobacco plants. Plant Physiol. Biochem. 37(4): 273−282.
    126. Marron, N. , E. Dreyer, E. Boudouresque, D. Delay, J.M. Petit, F.M. Delmotte, and F. Brignolas.2003. Impact of successive drought and re-watering cycles on growth and specific leaf area of two Populus canadensis (Moench) clones, “Dorskamp” and “Luisa_Avanzo. Tree physiol. 23(18): 1225-1235.
    127. Martin, E. , M.E. Donkin, and R.A. Stevens.1993. Stomata Studies in Biology. Edward Arnold Limited, London.
    128. Martini, D. , C. Del Bo,M. Tassotti, P. Rso, D. Del Rio, F. Brighenti, and M. Porrini.2016. Coffee Consumption and Oxidative Stress: A Review of Human Intervention Studies. Molecules. 21(8): 1-20
    129. Matsumoto, S.N. , G.O. Faria, V.S. A.E.S. Viana Rocha,, and A.B. de Novaes.2006. Water relations in a coffee grove planted with grevilleas in Vitoria da conquista, Bahia, Brazil. Coffee Science, Lavras 1(1): 71-83.
    130. Mazzafera, P. and S. Warrior.1991. The coffee yield. Campinas: IAC, P 21.
    131. Mazzafera, P. and J.P.F. Teixeira.1989. Prolina em cafeeiros submetidos a déficit hídrico. Turrialba 39: 305-313
    132. McDonald, M.S. 2003. Photobiology in higher plants. Chichester: John Wiley and Sons. https://www.wiley.com/en-us/Photobiology+of+Higher+Plants-p-9780470855232.
    133. Meinzer, F.C. , G. Goldstein, and D.A. Grantz.1990. Carbon isotope discrimination in coffee genotypes grown under limited water supply. Plant Physiol. 92(1): 130-135.
    134. Mendez-Lopez, I. , R. Basurto-Rios, and J.E. Ibarra.2003. Bacillus thuringiensis serovar israelensis is highly toxic to the coffee berry borer, Hypothenemus hampei! Ferr. Coleoptera :Scolytidae) Fems. Micro. biol. Lett. 226(1): 73-77.
    135. Menendez, R., A. Gonzalez, J.K. Hill, B. Braschler, S. Willis, Y. Collingham, R.Fox, D.B. Roy, and C.D. Thomas.2006. Species richness changes lag behind climate change. Proceedings of the Royal Society B: Biol. Sci. 273(1593): 1465-1470.
    136. Mishra, M.K. and H.L. Sreenath.2004. High Efficiency Agrobacterium mediated transformation of Coffee (Coffee canephora Pierre ex. Frohner) using hypocotyls explants. In: Proceedings of the 19th ASIC Colloquium. Bangalore, India, pp. 792-796.
    137. Mishra, M.K. , H.L. Sreenath, and Jayarama.2008. Agrobacterium strain and antibiotics selection regime improve the production of transgenic coffee plants,” in Proceedings of the 22nd International association for coffee science (ASIC ’08), pp. 843-850, Campinas, Brazil
    138. Mittler, R. 2002. Oxidative stress, antioxidants and stress tolerance. Trends Plant Sci. 7(9): 405-410.
    139. MOA.2003. Coffee Development and Marketing Comprehensive Plan (in Amharic). Ministry of Agriculture (MOA), Addis Ababa, Ethiopia.
    140. Mofatto, L.S., F.A. Carneiro, N.G.Vieira, K.E. Duarte, R.O. Vidal, G.C. Alekcevetch, M.G. Cotta, J.L. Verdeil, F.L. Montes, M. Lartaud, T. Leroy, F.D. Bellis, D. Pot, G.C. Rodrigues, M.F. Carazzolle, G.A.G. Pereira, A.C. Andrade, and Marraccini.2016. Identification of candidate genes for drought tolerance in coffee by high-throughput sequencing in the shoot apex of different Coffea arabica cultivars. BMC Plant Biol. 16 (94): 1-18
    141. Mondolot, L. , P. Fisca, B. Buatois, E. Talansier, A. Kochiko, and C. Campa.2006. Evolution in caffeoylquinic acid content and histolocalization during Coffea canephora leaf development. Ann. Bot. 98(1): 33-40.
    142. Monteiro, M.C. and A. Farah.2012. Chlorogenic acids in Brazilian C. arabica cultivars from various consecutive crops. Food Chem. 134(1): 611-614.
    143. Morais, H. , C.J. Marur, P.H. Caramori, M.A. Ribeiro, and J.C. Gomes.2003. Physiological characteristics and growth of coffee plants grown under shade of pigeonpea and unshaded. Pesq. Agropec. Bras .38(10): 1131-1137.
    144. Narayana, K.R. , M.S. Reddy, M.R. Chaluvadi, and D.R. Krishna.2001. Bioflavonoids classification, pharmacological, biochemical effects and therapeutic potential. I. J. Pharmacol. 33(1): 2-16.
    145. Naveed, S. , M. Aslam, M.A. Maqbool, S. Bano, Q.U. Zaman, and R.M. Ahmad.2014. Physiology of High Temperature Stress Tolerance at Reproductive Stages in Maize. J. Anim. Plant. Sci. 24(4): 1141-1145.
    146. Neill, S. , R. Desikan, and J. Hancock.2002. Hydrogen peroxide signaling. Curr. Opini. Plant Biol. 5(5): 388-395.
    147. Nesper, M. , C. Kueffer, S. Krishnan, C.G. Kushalappa, and J. Ghazoul.2011. Shade coffee in Hawai ‘i - Exploring some aspects of quality, growth, yield, and nutrition. Scienti. Horti. 128(2): 152-158.
    148. Nguyen, S. and K. Hunseung.2017. An endoplasmic reticulumlocalized Coffea arabica BURP domain-containing protein affects the response of transgenic, Arabidopsis plants to diverse abiotic stresses. Plant Cell Rep. 36(11): 1829-1839.
    149. Nguyen, S. , T.Z.T. Sai, G. Nawaz, K. Lee, and H. Kang.2016. Abiotic stresses affect differently the intron splicing and expression of chloroplast genes in coffee plants (Coffea arabica) and rice (Oryza sativa). J. Plant Physiol. 201(142): 85-94.
    150. Niyogi, K.K. 1999. Photo protection revisited: genetic and molecular approaches. Annu. Rev. Plant Phys. 50: 333-359.
    151. Nkondjock, A. 2009. Coffee consumption and the risk of cancer. An overview. Cancer Lett. 277(2): 121-125.
    152. Noctor, G. , R. De Paepe, and C.H. Foyer.2007. Mitochondrial redox biology and homeostasis in plants. Trends Plant Sci. 12(3): 125-134.
    153. Noctor, G. and C.H. Foyer.1998. Ascorbate and glutathione: keeping active oxygen under control”. Annu. Rev. Plant Biol. 49(1): 249-279.
    154. Nunes, M.A. 1976. Water relations in coffee: significance of plant water deficits to growth and yield: A review. J. Coffee Res. 6: 4-21.
    155. Nunes, M.A. , D.C. Ramalho, and M.A. Dias.1993. Effect of nitrogen supply on the photosynthetic performance of leaves from coffee plants exposed to bright light. Jour. Exp. Bot. 44(262): 893-899.
    156. Ogita, S. , H. Uefuji, M. Morimoto, and H. Sano.2004. Application of RNAi to confirm theobromine as the major intermediate for caffeine biosynthesis in coffee plants with potential for construction of decaffeinated varieties. Plant Mol. Biol. 54(6): 931-941.
    157. Palakolanu, S.R. , V. Thirulogachandar, C.S. Vaishnavi, A. Aakrati, K. Sudhir, S.K. Sopory, and K.R. Malireddy.2011. Molecular characterization and expression of a gene encoding cytosolic hsp90 from Pennisetum glaucum and its role in abiotic stress adaptation. Gene. 474(1-2): 29-38.
    158. Paiva, L.C. , R.J. Guimarães, and A.S. Souza.2003. Influence of different shading levels on coffee (Coffea arabica L.) seedlings growth. Cienc Agrotec .27(1): 134-140.
    159. Park, Y.J. , J.W. Lee, and J.J. Han.2019. Weekly economic review: Five trends changes and prospects in the coffee industry. Hyundai Research Institute. 848: 19-25.
    160. Parvaiz, A. and S. Satyawati.2008. Salt stress and phyto-biochemical responses of plants - A review. Plant soil. Environ. 54(3): 89-99.
    161. Patay, E.B. , T. Bencsik, and N. Papp.2016. Phytochemical overview and medicinal importance of coffea species from the past until now. Asian pacific J. Tropic. Med. 9(12): 1127-1135.
    162. Perfecto, I. and I. Armbrecht.2003. The coffee agroecosystem in the neotropics: Combining ecological and economic goals, CRC. Press L. L. C. 12.
    163. Perthuis, B. , J.L. Pradon, C. Montagnon, M. Dufour, and T. Leroy.2005. Stable resistance against the leaf miner Leucoptera coffeella expressed by genetically transformed Coffea canephora in a pluriannual field experiment in French Guiana. Euphytica. 144(3): 321-329.
    164. Peter, J. , K. Wilson Thompson, and G.H. John.2002. Specific leaf area and leaf dry matter content as alternative predictors of plant strategies. New Phytol. 143(1): 155-162.
    165. Pinheiro, H.A. , F.M. Da Matta, A.R.L. Chaves, M.E. Loureiro, and C. Ducatti.2005. Drought tolerance is associated with rooting depth and stomatal control of water use in clones of Coffea canephora. Ann. Bot. 96(1): 101-108.
    166. Pompelli, M.F. , S.C.V. Martins, W.C. Antunes, A.R.M. Chaves, and F.M. Da Matta.2010. Photosynthesis and photoprotection in coffee leaves is affected by nitrogen and light availabilities in winter conditions. J. Plant Physiol. 167(13): 1052-1060.
    167. Priscilla, N. , P. Camila, P.W. Fernanda, and C. Marcelo.2016. Characterization of the Promoter of the Homeobox Gene CaHB12 in Coffea Arabica.Trop. Pla.Biol. 9(1): 1-13
    168. Racchi, M.L. , F. Bagnoli, I. Balla, and S. Danti.2001. Differential activity of catalase and superoxide dismutase in seedlings and in vitro micropropagated oak (Quercus robur L.). Plant Cell Rep. 20(2): 169-174.
    169. Ramalakshmi, K. , I.R. Kubra, and L.J.M. Rao.2008. Antioxidant potential of low-grade coffee beans. Food Res. Inter. 41(1): 96-103.
    170. Ramalho, J.C. , A.P. Rodrigues, F.C. Lidon, L.M.C. Marques, A.E. Leitão, and A.S. Fortunato.2018. Stress cross-response of the antioxidative system promoted by superimposed drought and cold conditions in Coffea spp. PLoSONE. 13(6): 1-19
    171. Reih, P.B. , D.S. Ellsworth, and M.B. Walters.2002. Leaf structure (specific leaf area) modulates photosynthesis-nitrogen relations: evidence from within and across species and functional groups. Funct. Ecol. 12(6): 948-958.
    172. Reis, A.R. , J.L. Favarin, E. Malavolta, J.L. Junior, and M.F. Moraes.2009. Photosynthesis, chlorophylls and SPAD readings in coffee leaves in relation to nitrogen supply. Commun. Soil Sci. Plan. 40(9-10): 1512-1528.
    173. Ribas, A.F. , A.K. Kobayashi, R.M. Galvão, J.C. Bespalhok Filho, L.F.P. Pereira, and L.G.E. Vieira.2001. Transformacao de Coffea canephora P. com gene para resistencia ao glufosinato de amonio usando bombardeamento de particulas. In: Anais do II Simposio de Pesquisa sobre os Cafes do Brasil. Vitoria, Espirito Santo, pp.34.
    174. Ribas, A.F. , A.K. Kobayashi, L.F.P. Pereira, and L.G.E. Vieira.2005. Genetic transformation of Coffea canephora by particle bombardment. Biol Plantarum. 49(4): 493-497.
    175. Rinkus, S.J. and R.T. Taylor.1990. Analysis of hydrogen peroxide in freshly prepared coffee. Food Chem. Toxicol. 28(5): 323-331.
    176. Roberts, M. 2013. Preface: Induced Resistance to biotic stress. J. Exp. Bot. 64(5): 1235-1236.
    177. Rodrigues, W.P. , J.R. Silva, L.S. Ferreira, J.A.M.H. Filho, F.A.M.M.A. Figueiredo, T.M. Ferraz, and E. Campostrini.2018. Stomatal and photochemical limitations of photosynthesis in coffee (Coffea spp.) plants subjected to elevated temperatures. Crop Pasture Sci. 69(3): 317-325.
    178. Rodríguez, L. , J. Verdean, L. Arias, R. Medina, and E. Velasco.2001. Growth, relative water content, transpiration and photosynthetic pigment content in coffee trees (Coffea arabica L.) growing at different sunlight regimes. Cultivos Tropic. 22(4): 37-41.
    179. Rolland, F. and J. Sheen.2005. Sugar sensing and signaling networks in plants. Biochem. Soc. Trans. 33(1): 269-271.
    180. Rolland, F. , E.B. Gonzalez, and J. Sheen.2006. Sugar sensing signaling in plants: Conserved and novel mechanisms. Annu. Rev. Plant boil. 57: 675-709.
    181. Rosa, M. , C. Prado, G. Podazza, R. Interdonato, J.A. Gonzalez, M. Hilal, and F.E. Prado.2009. Soluble sugars- metabolism, sensing and abiotic stress. Plant Signal. Behav. 4(5): 388-393.
    182. Rosillo, A.G. , J.R. Acuna, A.L. Gaitan, and M. Pena.2003. Optimized DNA delivery into Coffea arabica suspension culture cells by particle bombardment. Plant Cell Tiss. Org. 74(1): 45-49.
    183. Ross-Karstens, G.S. , G. Ebert, and P. Ludders.1998. Influence of in vitro growth conditions on stomatal density, index and aperture of grape, coffee and banana plantlets. Plant Tissue Culture Biotechnol. 4: 21-27.
    184. Salehi-Lisar, S.Y. and A.H. Bakhshayeshan.2016. Drought Stress in Plants: Causes, Consequences, and Tolerance. In: Hossain M., S. Wani, S. Bhattacharjee, D. Burritt, and L.S. Tran (eds). Drought Stress Tolerance in Plants. Vol 1: pp. 1-17 Springer. Cham. ISBN 978-3-319-28899-4.
    185. Santana-Buzzy, N. , R. Rojas-Herrara, R.M. Galaz-Avalos, J.R. Ku-Cauich, J. Mijangos- Cortes, L.C. Gutierrez-Pancheco, A. Canto, F. Quiroz-Figueroa, and V.M. Loyola-Vargas.2007. Advances in coffee tissue culture and its practical applications. In Vitro Cell Dev. Biol. Plant. 43(6): 507-520.
    186. Scandalios, J.G. 1993. Oxygen stress and superoxide dismutases. Plant Physiol. 101(1): 7-12.
    187. Sharma, P. , A.B. Jha, and R.S. Dubey.2010. Oxidative stress and antioxidative defense system in plants growing under abiotic stresses. in Handbook of plant and crop stress, M. Pessarakli, Ed., pp. 89-138, CRC Press, Taylor and Francis Publishing Company, Fla, USA, 3rd edition
    188. Sharma, P. , J.A. Bhusan, D. Rama Shanker, and M. Pessarakli.2012. Reactive oxygen species, oxidative damage, and antioxidative defense mechanism in plants under stressful conditions. J. Bot. 2012: 1-26.
    189. Shapiguzov, A. , J.P. Vainonen, M. Wrzaczek, and J. Kangasjärvi.2012. ROS-talk - how the apoplast, the chloroplast, and the nucleus get the message through. Front Plant Sci. 292 (3): 1-9.
    190. Sheen, J. 1999. C4 gene expression. Ann. Rev. Plant Physiol. Plant Mol. Biol. 50: 187-217.
    191. Shimber, G.T. , M.R. Ismail, H. Kausar, M. Marziah, and M.F. Ramlan.2013. Plant water relations, crop yield and quality in coffee (Coffea arabica L.) as influenced by partial root zone drying and deficit irrigation. Aust. J. crop sci. 7(9): 1361-1368.
    192. Siamsa, M. , M.D. Doyle, and F.C. Paul.2010. Chloroplast and reactive oxygen species involvement in apoptotic-like programmed cell death in Arabidopsis suspension cultures. J. Exp. Bot. 61(2): 473-482.
    193. Silva, E.A. and P. Mazzafera.2008. Influence of temperature and water on coffee culture. The Ameri. J. Plant Sci. Biotechnol. Global science books
    194. Silva, K.J.P. , N. Mahna, Z. Mou, and K.M. Folta.2018. NPR1 as a transgenic crop protection strategy in horticultural species. Hortic. Res. 5(1): 1-15.
    195. Silva, E.A. , F.M. Da Matta, C. Ducatti, A.J. Regazzi, and R.S. Barros.2004. Seasonal changes in vegetative growth and photosynthesis of Arabica coffee trees. Field Crops Res. 89: 349-357.
    196. Singla, J. and S.G. Krattinger.2016. Biotic stress resistance genes in wheat. Reference module in food science.
    197. Smeekens, S. 2000. Sugar-induced signal transduction in plants. Ann. Rev Plant Physiol. Plant Mol. Biol. 51(1): 49-81.
    198. Smith, W. , R. Desjardins, and B. Grant.2008. Some perspectives on agricultural GHG mitigation and adaptation strategies with respect to the impact of climate change-variability in vulnerable areas. In: symposium on climate change and variability: Agro-meteorological monitoring and coping strategies for agriculture. Oscarsborg, Norway. Abstract Oscarsborg: WMO, p. 44
    199. Sokolik, A. and V. Yurin.2014. Stress-induced electrolyte leakage: the role of K+-permeable channels and involvement in programmed cell death and metabolic adjustment. J. Exp. Bot. 65(5): 1259-1270.
    200. Söndahl, M. R. and V.H.A.M. Van der.2005. The plant: Origin, production and botany. In Illy, Andrea; Viani, Rinantonio. Espresso Coffee: The Science of Quality (Second ed.). Elsevier Academic Press. p.21.ISBN978-0-12-370371-2.eBook ISBN:9780080575360
    201. Spiral, J. and V. Petiard.1991. Protoplast culture and regeneration in coffee species. In: Proceedings of the 14th ASIC Colloquium, San Francisco, USA, pp.383-391.
    202. Stalikas, C.D. 2007. Extraction, separation, and detection methods for phenolic acids and flavonoids. J. Sep. Sci. 30(18): 3268-3295.
    203. Steiman, S. , T. Idol, H.C. Bittenbender, and L. Gautz.2011. Shade coffee in Hawai exploring some aspects of quality, growth, yield, and nutrition. Sci. Hortic. 128(2): 152-158.
    204. Sugiyama, M. , C. Matsuoka, and T. Takagi.1995. Transformation of Coffee with Agrobacterium rhizogenes. In: Proceedings of the 16th ASIC Colloquium, Kyoto, Japan, pp.853-859
    205. Szabados, L. and A. Savoure.2010. Proline: a multifunctional amino acid. Trends Plant Sci. 15(2): 89-97.
    206. Taye Kufa.2006. Ecophysiological diversity of wild Arabica coffee populations in Ethiopia: Growth, water relation and hydraulic characteristics along a climatic gradient. Ecology and Development Series, No. 46. Cuvillier Verlag, Gottingen (PDF) Montane Rainforest with Wild Coffee arabica in the Bonga Region (SW Ethiopia): Plant Diversity, Wild Coffee Management and Implications for Conservation. Available from https://www.researchgate.net/publication/262514208
    207. Taye, K. and B. Jurgen.2011. Stomatal characteristics in arabica coffee germplasm accessions under contrasting environments at Jimma, southwestern Ethiopia. Inter. J. Bot. 7(1): 63-72.
    208. Tesfaye, S.G. , M.R. Ismail, M.F. Ramlan, M. Marziah, and H. Kausar.2014. Effect of soil drying on rate of stress development, leaf gas exchange and proline accumulation in robusta coffee (Coffea canephora Pierre Ex Froehner) clones. Exp. Agricul. 50(3): 458-479.
    209. Thomas, C.D. , A. Cameron, R.E. Green, M. Bakkenes, L.J. Beaumont, Y.C. Collingham, B.F. Erasmus, M.F. De Siqueira, A. Grainger, L. Hannah, L. Hughes, B. Huntley, A.S. Van Jaarsveld, G.F. Midgley, L. Miles, M.A. Ortega- Huerta, A.T. Peterson, O.L. Phillips, and S.E. Williams.2004. Extinction risk from climate change. Nature. 427(6970): 145-148.
    210. Torres, L.F. , E. Dechamp, G.S.C. Alves, L.E.C. Diniz, L.V. Paiva, J.C. Breitler, A.C. Andrade, P. Marraccini, and H. Etienne.2016. Influence of abiotic stresses in phenotypic expression of transgenic plants of Coffea arabica under action CcDREB1D promoter. In: 26th International Conference on Coffee Science. Kunming, China: Association for Science and Information on Coffee (ASIC), B2.
    211. Tounekti, T. , M. Mosbah, T.A.A. Turki, and H. Khemira.2018. Water relations and photo-protection mechanisms during drought stress in four coffees (Coffee arabica) cultivars from south western Saudi Arabia. S. African J. Bot. 117(59): 17-25.
    212. Uefuji, H. , S. Ogita, Y. Yamaguchi, N. Koizumi, and H. Sano.2003. Molecular cloning and functional characterization of three distinct N-Methyltransferases involved in the caffeine biosynthetic pathway in coffee plants. Plant Physiol. 132(1): 372-80.
    213. Ursula, K.S. and H.F. Leslie.1992. Flowering, ethylene production, and ion leakage of coffee in response to water stress and gibberellic acid. J. Amer. Soc. Hort. Sci. 117(1): 158-163.
    214. Vaast, P. , J. Angrand, N. Franck, J. Dauzat, and M. Génard.2005. Fruit load and ring-barking affect carbon allocation and photosynthesis of leaf and fruit of Coffea arabica in the field. Tree Physiol 25:753-760.
    215. Van Boxtel, J. , M. Berthouly, C. Carasco, M. Dufour, and A. Eskes.1995. Transient expression of beta-glucuronidase following biolistic delivery of foreign DNA into coffee tissues. Plant Cell Rep. 14(12): 748-752.
    216. Van Boxtel, J. , A. Eskes, and M. Berthouly.1995. Glufosinate as an efficient inhibitor of callus proliferation in coffee tissue. InVitro Cell Dev. Biol. Plant. 33(1): 6-12.
    217. Verbruggen, N. and C. Hermans.2008. “Proline accumulation in plants: a review”. Amino Acids. 35(4): 753-759.
    218. Vinod Kumar, K. V. , A. Satyanarayana, A. Ramakrishna, A. Chandrashekar, and G.V. Ravishankar.2007. Evidence for localization of N-methyltransferase (NMT) of caffeine biosynthetic pathway in vacuolar surface of Coffea canephora endosperm elucidated through localization of GUS reporter gene driven by NMT promoter. Curr. Science. 93(3): 383- 386.
    219. Vinod Kumar, K.V. , S. Satyanarayana, I. Sarala, E.P. Indu, P. Giridhar, A. Chandrashekar, and G.A. Ravishankar.2006. Stable transformation and direct regeneration in Coffea canephora P ex Fr by Agrobacterium rhizogenes mediated transformation without hairy-root phenotype. Plant cell Rep. 25(3): 214-222.
    220. Weis, E. and J.A. Berry.1988. Plants and high temperature stress. Symposia of the society for the experimental biology. 42: 329-46.
    221. Wery, J. , S.N. Silim, E.J. Knights, R.S. Malhotra, and R. Cousin.1994. Screening techniques and sources and tolerance to extremes of moisture and air temperature in cool season food legumes. Euphotic. 73(1): 73-83.
    222. Wiart, C. 2006. Ethno pharmacology of medicinal plants. Asia and the Pacific. Totowa: Humana Press. 167-168.ISBN 1-58829-748-9 (Alk. paper). pp.1-219.
    223. Willekens, H. , D. Inze, M. Van Montagu, and W. Van Camp.1995. Catalases in plants. Mol. Breeding. 1(3): 207-228.
    224. Willmer, C. and M. Fricker.1996. Stomata. 2nd Ed., Chapman and Hall, London.
    225. Wintgens, J.N. 2004. Coffee: Growing, Processing, Sustainable Production. A guide for Growers, Traders and Researchers. Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim, Germany.
    226. Worku, M. and T. Astatkie.2010. Dry matter partitioning and physiological responses of Coffea arabica varieties to soil moisture deficit stress at the seedling stage in southwest Ethiopia. Afri. J. Agricul. Res. 5(15): 2066-2072.
    227. Yan, J. , N. Tsuichihara, T. Etoh, and S. Iwai.2007. Reactive oxygen species and nitric oxide are involved in ABA inhibition of stomatal opening. Plant Cell Environ. 30(10): 1320-1325.