γ-Aminobutyric Acid (GABA) Priming Improves Seed Germination and Seedling Stress Tolerance Associated With Enhanced Antioxidant Metabolism, DREB Expression, and Dehydrin Accumulation in White Clover Under Water Stress

As an important plant growth regulator, the role of γ-aminobutyric acid (GABA) in regulating seeds germination was less well elucidated under water stress. The present study was conducted to investigate the impact of GABA pretreatment on seeds germination of white clover (Trifolium repens) under water deficient condition. Results demonstrated that seeds pretreated with 2μmol/l GABA significantly alleviated decreases in endogenous GABA content, germination percentage, germination potential, germination index, root length, and fresh weight along with marked reduction in mean germination time after 7days of germination under drought stress. In addition, seeds priming with GABA significantly increased the accumulation of soluble sugars, non-enzymatic antioxidants [reduced ascorbate, dehydroascorbic acid, oxidized glutathione (GSSG), and reduced glutathione (GSH)], and enzymes [superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), glutathioe reductase, and monodehydroasorbate reductase (MDHR)] activities involved in antioxidant metabolism, which could be associated with significant reduction in osmotic potential and the accumulation of superoxide anion, hydrogen peroxide, electrical leakage, and malondialdehyde in seeds under drought stress. The GABA-pretreated seeds exhibited significantly higher abundance of dehydrin (DHN, 56 KDa) and expression levels of DHNs encoding genes (SK2, Y2K, Y2SK, and Dehydrin b) and transcription factors (DREB2, DREB3, DREB4, and DREB5) than the untreated seeds during germination under water-limited condition. These results indicated that the GABA regulated improvement in seeds germination associated with enhancement in osmotic adjustment, antioxidant metabolism, and DREB-related DHNs expression. Current study will provide a better insight about the GABA-regulated defense mechanism during seeds germination under water-limited condition.

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Diethyl Aminoethyl Hexanoate Priming Ameliorates Seed Germination via Involvement in Hormonal Changes, Osmotic Adjustment, and Dehydrins Accumulation in White Clover Under Drought Stress

Frontiers in Plant Science ◽

10.3389/fpls.2021.709187 ◽

2021 ◽

Vol 12 ◽

Author(s):

Muhammad Jawad Hassan ◽

Wan Geng ◽

Weihang Zeng ◽

Muhammad Ali Raza ◽

Imran Khan ◽

...

Keyword(s):

Drought Stress ◽

Seed Germination ◽

White Clover ◽

Osmotic Adjustment ◽

Soluble Sugars ◽

Seed Vigor ◽

Starch Degradation ◽

Diethyl Aminoethyl Hexanoate ◽

The Impact ◽

Seeds Germination

Drought is a serious outcome of climate change reducing the productivity of forage species under arid and semi-arid conditions worldwide. Diethyl aminoethyl hexanoate (DA-6), a novel plant growth regulator, has proven to be involved in the amelioration of critical physiological functions in many agricultural crops under various abiotic stresses, but the role of the DA-6 in improving seed germination has never been investigated under drought stress. The present study was carried out to elucidate the impact of the DA-6 priming on seeds germination of white clover under drought stress. Results showed that seed priming with the DA-6 significantly mitigated the drought-induced reduction in germination percentage, germination vigor, germination index, seed vigor index, root length, shoot length, and fresh weight after 7 days of seed germination. The DA-6 significantly increased the endogenous indole-3-acetic acid, gibberellin, and cytokinin content with marked reduction in abscisic acid content in seedlings under drought stress. In addition, the DA-6 significantly accelerated starch catabolism by enhancing the activities of hydrolases contributing toward enhanced soluble sugars, proline content and ameliorated the antioxidant defense system to enhance the ability of reactive oxygen species scavenging under drought stress. Furthermore, exogenous DA-6 application significantly increased dehydrins accumulation and upregulated transcript levels of genes encoding dehydrins (SK2, Y2SK, or DHNb) during seeds germination under water deficient condition. These findings suggested that the DA-6 mediated seeds germination and drought tolerance associated with changes in endogenous phytohormones resulting in increased starch degradation, osmotic adjustment, antioxidants activity, and dehydrins accumulation during seed germination under water deficient condition.

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Pretreatment with NaCl Promotes the Seed Germination of White Clover by Affecting Endogenous Phytohormones, Metabolic Regulation, and Dehydrin-Encoded Genes Expression under Water Stress

International Journal of Molecular Sciences ◽

10.3390/ijms19113570 ◽

2018 ◽

Vol 19 (11) ◽

pp. 3570

Author(s):

Yiqin Cao ◽

Linlin Liang ◽

Bizhen Cheng ◽

Yue Dong ◽

Jiaqi Wei ◽

...

Keyword(s):

Water Stress ◽

Seed Germination ◽

White Clover ◽

Metabolic Regulation ◽

Soluble Sugars ◽

Germination Percentage ◽

Membrane Lipid ◽

Antioxidant Metabolism ◽

Stress Damage ◽

Seeds Germination

This study was designed to examine the effects of NaCl pretreatment on the seed germination of white clover (Trifolium repens cv. Ladino) under water stress induced by 19% polyethylene glycol (PEG) 6000. Lower concentrations of NaCl (0.5, 1, and 2.5 mM) pretreatment significantly alleviated stress-induced decreases in germination percentage, germination vigor, germination index, and radicle length of seedlings after seven days of germination under water stress. The soaking with 1 mM of NaCl exhibited most the pronounced effects on improving seed germination and alleviating stress damage. NaCl-induced seeds germination and growth could be associated with the increases in endogenous gibberellic acid (GA) and indole-3-acetic acid (IAA) levels through activating amylases leading to improved amylolysis under water stress. Seedlings pretreated with NaCl had a significantly lower osmotic potential than untreated seedlings during seed germination, which could be related to significantly higher soluble sugars and free proline content in NaCl-treated seedlings under water stress. For antioxidant metabolism, NaCl pretreatment mainly improved superoxide dismutase, peroxidase, ascorbate peroxidase, and glutathione reductase activities, transcript levels of FeSOD, APX, and DHAR, and the content of ascorbic acid, reduced glutathione, and oxidized glutathione during seed germination under water stress. The results indicated that seeds soaking with NaCl could remarkably enhance antioxidant metabolism, thereby decreasing the accumulation of reactive oxygen species and membrane lipid peroxidation during germination under water stress. In addition, NaCl-upregulated dehydrin-encoded genes SK2 expression could be another important mechanism of drought tolerance during seeds germination of white clover in response to water stress.

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Alterations of Endogenous Hormones, Antioxidant Metabolism, and Aquaporin Gene Expression in Relation to γ-Aminobutyric Acid-Regulated Thermotolerance in White Clover

Antioxidants ◽

10.3390/antiox10071099 ◽

2021 ◽

Vol 10 (7) ◽

pp. 1099

Author(s):

Hongyin Qi ◽

Dingfan Kang ◽

Weihang Zeng ◽

Muhammad Jawad Hassan ◽

Yan Peng ◽

...

Keyword(s):

Gene Expression ◽

High Temperature ◽

Temperature Stress ◽

White Clover ◽

High Temperature Stress ◽

Aminobutyric Acid ◽

Endogenous Hormones ◽

Gaba Level ◽

Antioxidant Metabolism ◽

The Impact

Persistent high temperature decreases the yield and quality of crops, including many important herbs. White clover (Trifolium repens) is a perennial herb with high feeding and medicinal value, but is sensitive to temperatures above 30 °C. The present study was conducted to elucidate the impact of changes in endogenous γ-aminobutyric acid (GABA) level by exogenous GABA pretreatment on heat tolerance of white clover, associated with alterations in endogenous hormones, antioxidant metabolism, and aquaporin-related gene expression in root and leaf of white clover plants under high-temperature stress. Our results reveal that improvement in endogenous GABA level in leaf and root by GABA pretreatment could significantly alleviate the damage to white clover during high-temperature stress, as demonstrated by enhancements in cell membrane stability, photosynthetic capacity, and osmotic adjustment ability, as well as lower oxidative damage and chlorophyll loss. The GABA significantly enhanced gene expression and enzyme activities involved in antioxidant defense, including superoxide dismutase, catalase, peroxidase, and key enzymes of the ascorbic acid–glutathione cycle, thus reducing the accumulation of reactive oxygen species and the oxidative injury to membrane lipids and proteins. The GABA also increased endogenous indole-3-acetic acid content in roots and leaves and cytokinin content in leaves, associated with growth maintenance and reduced leaf senescence under heat stress. The GABA significantly upregulated the expression of PIP1-1 and PIP2-7 in leaves and the TIP2-1 expression in leaves and roots under high temperature, and also alleviated the heat-induced inhibition of PIP1-1, PIP2-2, TIP2-2, and NIP1-2 expression in roots, which could help to improve the water transportation and homeostasis from roots to leaves. In addition, the GABA-induced aquaporins expression and decline in endogenous abscisic acid level could improve the heat dissipation capacity through maintaining higher stomatal opening and transpiration in white clovers under high-temperature stress.

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FOLIAGE APPLIED SILICON AMELIORATES DROUGHT STRESS THROUGH PHYSIO-MORPHOLOGICAL TRAITS, OSMOPROTECTANTS AND ANTIOXIDANT METABOLISM OF CAMELINA (Camelina sativa L.) GENOTYPES

Acta Scientiarum Polonorum Hortorum Cultus ◽

10.24326/asphc.2021.4.4 ◽

2021 ◽

Vol 20 (4) ◽

pp. 43-57

Author(s):

Zahoor Ahmad ◽

Ejaz Ahmad Warraich ◽

Muhammad Aamir Iqbal ◽

Celaleddin Barutçular ◽

Hesham Alharby ◽

...

Keyword(s):

Water Stress ◽

Drought Stress ◽

Chlorophyll Content ◽

Foliar Application ◽

Negative Impact ◽

Turgor Pressure ◽

Water Relation ◽

Stress Conditions ◽

Antioxidant Metabolism ◽

The Impact

Silicon (Si) is one of the best plant defense elements against the biotic and abiotic stresses. Camelina plants accumulate Si which serves in protection against drought stress. The present study was conducted to investigate the impact of different doses of foliage applied Si (0, 3, 6 and 9 mM) under water stress (40% field capacity, FC) and non-stress conditions (100% FC) on camelina genotypes (Canadian and Australian). The imposed drought drastically decreased the growth parameters like root-shoot length and plant fresh and dry weight and also had negative impact on the chlorophyll content along with water relation attributes (water potential, osmotic potential and turgor pressure). In contrast, total free amino acids, total soluble proteins, proline and antioxidants such as ascorbic peroxidase (APX), superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) were enhanced especially in water stressed Canadian genotype, while osmoprotectants (flavonoids, anthocyanins and glycinebetaine) and phenolics contents were decreased. On the other hand, the foliar application of Si was instrumental in enhancing the growth of camelina by increasing the chlorophyll contents and water relation of stressed and non-stressed plants. Similarly, the biochemical, osmoprotectants and antioxidant metabolism was also improved in camelina stressed plants through the application of foliar Si. In conclusion, foliar application of 6 mM Si at vegetative growth stage played a vital role in alleviating the drastic impact of water stress on camelina growth by improving the water status, chlorophyll content, accumulation of phenolics and osmoprotectants and activating antioxidants. Therefore, the foliar application of Si could be developed as an important biologically viable strategy for boosting the tolerance in camelina plants to water stress conditions.

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Research Progress and Perspective on Drought Stress in Legumes: A Review

International Journal of Molecular Sciences ◽

10.3390/ijms20102541 ◽

2019 ◽

Vol 20 (10) ◽

pp. 2541 ◽

Cited By ~ 29

Author(s):

Muhammad Nadeem ◽

Jiajia Li ◽

Muhammad Yahya ◽

Alam Sher ◽

Chuanxi Ma ◽

...

Keyword(s):

Water Stress ◽

Drought Stress ◽

Nutrient Uptake ◽

Nutrient Management ◽

Growth Parameters ◽

Photosynthetic Apparatus ◽

Net Photosynthesis ◽

Research Progress ◽

Drought Tolerant ◽

The Impact

Climate change, food shortage, water scarcity, and population growth are some of the threatening challenges being faced in today’s world. Drought stress (DS) poses a constant challenge for agricultural crops and has been considered a severe constraint for global agricultural productivity; its intensity and severity are predicted to increase in the near future. Legumes demonstrate high sensitivity to DS, especially at vegetative and reproductive stages. They are mostly grown in the dry areas and are moderately drought tolerant, but severe DS leads to remarkable production losses. The most prominent effects of DS are reduced germination, stunted growth, serious damage to the photosynthetic apparatus, decrease in net photosynthesis, and a reduction in nutrient uptake. To curb the catastrophic effect of DS in legumes, it is imperative to understand its effects, mechanisms, and the agronomic and genetic basis of drought for sustainable management. This review highlights the impact of DS on legumes, mechanisms, and proposes appropriate management approaches to alleviate the severity of water stress. In our discussion, we outline the influence of water stress on physiological aspects (such as germination, photosynthesis, water and nutrient uptake), growth parameters and yield. Additionally, mechanisms, various management strategies, for instance, agronomic practices (planting time and geometry, nutrient management), plant growth-promoting Rhizobacteria and arbuscular mycorrhizal fungal inoculation, quantitative trait loci (QTLs), functional genomics and advanced strategies (CRISPR-Cas9) are also critically discussed. We propose that the integration of several approaches such as agronomic and biotechnological strategies as well as advanced genome editing tools is needed to develop drought-tolerant legume cultivars.

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The impact of drought stress on the yields and food value of selected forage grasses

Acta Agrobotanica ◽

10.5586/aa.1663 ◽

2016 ◽

Vol 69 (2) ◽

Cited By ~ 4

Author(s):

Mariola Staniak

Keyword(s):

Soil Moisture ◽

Water Stress ◽

Drought Stress ◽

Dry Matter ◽

Nutritional Value ◽

Lolium Multiflorum ◽

Grass Species ◽

Forage Grasses ◽

The Impact

The aim of the study was to compare yields and nutritional value of selected species and cultivars of forage grasses under the optimal moisture conditions and long-term drought stress. The regenerative capacity of plants after dehydration was also assessed. The pot experiment was conducted in years 2009–2010 in IUNG-PIB’s greenhouse in Puławy, Poland. Nine cultivars of four species: Dactylis glomerata (‘Amera’, ‘Minora’), Festuca pratensis (‘Skra’, ‘Fantazja’), Festulolium braunii (‘Felopa’, ‘Agula’, ‘Sulino’), and Lolium multiflorum (‘Gisel’, ‘Lotos’) were investigated in well-watered conditions (70% field water capacity – FWC) and under a long-term drought stress (40% FWC).The study showed that stress caused by soil moisture deficiency significantly reduced yields of D. glomerata, F. pratensis, F. braunii, and L. multiflorum. The total yield of dry matter under stress conditions was about 31% lower, compared to the performance achieved on the optimally moisturized treatment. The smallest reduction in dry matter yield under the conditions of water deficit was recorded for D. glomerata, which makes it the most resistant to stress, followed by F. pratensis. The resistance of F. braunii and L. multiflorum to stress was similar and significantly lower. There was a various response of different grasses to the water stress. On the basis of the value of the DSI (drought susceptibility index), the tested cultivars were ranked depending on the sensitivity to drought, starting with the most resistant cultivar: ‘Minora’, ‘Skra’, ‘Fantazja’, ‘Amera’, ‘Sulino’, ‘Agula’, ‘Gisel’, ‘Lotos’, and ‘Felopa’. The digestibility of dry matter and nutrient value of the grasses depended on both the level of soil moisture and grass species. Under the water stress, the digestibility and protein value increased compared to the control objects. Lolium multiflorum and F. braunii had the best nutritional value, while D. glomerata – the weakest.

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Biochemical responses of Digitaria commutata and Cenchrus ciliaris to water stress: antioxidative reactions, proline and soluble sugars accumulation

Enero-Abril 2021 - Bioagro ◽

10.51372/bioagro333.3 ◽

2021 ◽

Vol 33 (3) ◽

pp. 171-180

Author(s):

Taoufik Amari ◽

Chedly Abdelly

Keyword(s):

Water Stress ◽

Soluble Sugars ◽

Antioxidant Enzyme Activities ◽

Stress Exposure ◽

Cenchrus Ciliaris ◽

Psii Photochemistry ◽

Mda Content ◽

The Impact ◽

Quantum Yield Of Psii ◽

Oxidative System

The impact of water stress on antioxidant enzyme activities, proline, soluble sugars, and carotenoids contents found in Digitaria commutata and Cenchrus ciliaris plants was investigated. Two different watering regimes were used on plants over a period of three months. Water stress decreased total chlorophyll content in plants, but increased carotenoids content. Interestingly, no change was observed in the quantum yield of PSII photochemistry (Fv/Fm). Malondialdehyde (MDA) content increased to a higher extent in both species. Enhanced activities of all the enzymes (peroxidase, catalase, and superoxide dismutase) studied, except for catalase in the roots were observed. Proline and soluble sugars contents increased significantly following water stress exposure. No clear differences were found between both species. The results link drought tolerance of Digitaria commutata and Cenchrus ciliaris plants with better capabilities of anti-oxidative system. Additionally, it is linked to the accretion of osmoprotectants proline and soluble sugars when exposed to drought.

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Response of ungrafted and grafted grapevine cultivans and rootstocks (Vitis sp.) to water stress

OENO One ◽

10.20870/oeno-one.2007.41.2.853 ◽

2007 ◽

Vol 41 (2) ◽

pp. 85 ◽

Cited By ~ 3

Author(s):

Imene Toumi ◽

Wissal M'Sehli ◽

Soumaya Bourgou ◽

Neila Jallouli ◽

Asma Bensalem-Fnayou ◽

...

Keyword(s):

Water Stress ◽

Water Potential ◽

Dry Matter ◽

Soluble Sugars ◽

Water Shortage ◽

Stem Water Potential ◽

Matter Production ◽

Stem Water ◽

The Impact ◽

Progressive Water Stress

Aims: The responses of two Vitis vinifera cultivars (Cardinal and Superior Seedless) and two rootstocks (110R and SO4) to drought, the effect of grafting and the interactions of scion/rootstock were investigated.Methods and results: The vines were subjected to a progressive water stress in greenhouse controlled conditions. At the end of the water stress treatments, physiological analyses were carried out (stem water potential, dry matter production, soluble sugars, proline as well as ions Na+ and K+). Drought was expressed by the drop of the stem water potential in the stressed vines as compared to their controls. Furthermore, tolerance and sensitivity were linked to the accumulation of soluble sugars and proline as well as the equilibrium of K+ and Na+ in the leaves.Conclusion: When ungrafted, Cardinal was more tolerant to water stress than Superior Seedless. The grafted vines exhibited more vigour, moreover, the combination of Cardinal with SO4 and Superior Seedless with 110R revealed to be the advantageous associations under water stress.Significance and impact of study: This work has been carried out to investigate the differential responses of grapevine cultivars to drought stress and the impact of grafting under water shortage conditions.

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Ecotypic Morphological and Physio-Biochemical Responses of Two Differentially Adapted Forage Grasses, Cenchrus ciliaris L. and Cyperus arenarius Retz. to Drought Stress

Sustainability ◽

10.3390/su13148069 ◽

2021 ◽

Vol 13 (14) ◽

pp. 8069

Author(s):

Muhammad Adeel Ghafar ◽

Nudrat Aisha Akram ◽

Muhammad Hamzah Saleem ◽

Jianyong Wang ◽

Leonard Wijaya ◽

...

Keyword(s):

Drought Stress ◽

Soluble Sugars ◽

Field Capacity ◽

Research Area ◽

Grass Species ◽

Enzymatic Antioxidants ◽

Forage Grasses ◽

Cenchrus Ciliaris ◽

Salt Range ◽

Water Scarce

Crop performance and yield are the results of genotypic expression as modulated by continuous interaction with the environment. Among the environmental aspects, drought and salinity are the most important factors, which limit the forages, including grasses, on a global basis. Grass species have the ability to grow under low water conditions and can produce high dry yield, proteins, and energy in areas exposed to drought stress. For this purpose, we conducted the present study to understand the response of forage grasses under drought stress from two different regions (Salt Range and Faisalabad) of Punjab, Pakistan. Two ecotypes of each grass species (Cenchrus ciliaris L. and Cyperus arenarius Retz.) were grown in pots at the botanical research area, Government College University Faisalabad, Pakistan. A group of plants were subjected to drought stress (60% field capacity) and controlled (100% field capacity) after three weeks of seed germination. The results from the present study depicted that the fresh and dry weights of root and shoot were decreased significantly under drought conditions. Moreover, C. ciliaris of the Salt Range area showed more resistance and higher growth production under drought stress. The chlorophyll (a and b) contents were also decreased significantly, while MDA, total soluble sugars, and proline levels were increased significantly under water-limited environments in the C. arenarius of Salt Range area. Enzymatic antioxidants (superoxidase dismutase (SOD) and peroxidase (POD)) and leaf Na+ were significantly raised in C. arenarius under drought stress collected from the Faisalabad region. Cenchrus ciliaris showed higher level of H2O2, total soluble proteins, glycinebetaine, catalase (CAT) and POD compared to C. arenarius. It also retained more leaf and root Ca2+, and root K+ under drought stress. It was concluded from the study that C. ciliaris is more resistant to drought in biomass production collected from the Salt Range area. The results suggested that C. ciliaris can be more widely used as a forage grass under water-scarce conditions as compared to C. arenarius.

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Exogenous Gibberellic Acid or Dilute Bee Honey Boosts Drought Stress Tolerance in Vicia faba by Rebalancing Osmoprotectants, Antioxidants, Nutrients, and Phytohormones

Plants ◽

10.3390/plants10040748 ◽

2021 ◽

Vol 10 (4) ◽

pp. 748

Author(s):

Mostafa M. Rady ◽

Sara H. K. Boriek ◽

Taia A. Abd El-Mageed ◽

Mohamed A. Seif El-Yazal ◽

Esmat F. Ali ◽

...

Keyword(s):

Drought Stress ◽

Gibberellic Acid ◽

Vicia Faba ◽

Growth Regulators ◽

Faba Bean ◽

Soluble Sugars ◽

Nutrient Status ◽

Plant Performance ◽

Ion Leakage ◽

Enzymatic Antioxidants

The use of growth regulators such as gibberellic acid (GA3) and biostimulants, including diluted bee honey (Db-H) can improve drought tolerance in many crops, including the faba bean (Vicia faba L.). Db-H contains high values of osmoprotectants, mineral nutrients, vitamins, and many antioxidants making it an effective growth regulator against environmental stress effects. Therefore, the present study was planned to investigate the potential improvement in the faba bean plant performance (growth and productivity) under full watering (100% of crop evapotranspiration (ETc)) and drought stress (60% of ETc) by foliar application of GA3 (20 mg L−1) or Db-H (20 g L−1). The ameliorative impacts of these growth regulators on growth, productivity, physio-biochemical attributes, nutrient status, antioxidant defense system, and phytohormones were evaluated. GA3 or Db-H attenuated the negative influences of drought stress on cell membrane stability, ion leakage, relative water content, nutrient status, leaf pigments related to photosynthesis (chlorophylls and carotenoids), and efficiency of the photosystem II (PSII in terms of Fv/Fm and performance index), thus improving faba bean growth, green pod yield, and water use efficiency. Drought stress caused an abnormal state of nutrients and photosynthetic machinery due to increased indicators of oxidative stress (malondialdehyde (MDA), hydrogen peroxide (H2O2) and superoxide (O2•−)), associated with increased osmoprotectants (proline, glycine betaine, soluble sugars, and soluble protein), non-enzymatic antioxidants (ascorbic acid, glutathione, and α-tocopherol), and enzymatic antioxidant activities (superoxide dismutase, catalase, glutathione reductase, and ascorbate peroxidase). However, foliar-applied GA3 or Db-H mediated further increases in osmoprotectants, antioxidant capacity, GA3, indole-3-acetic acid, and cytokinins, along with decreased levels of MDA and abscisic acid. These results suggest the use of GA3 or Db-H at the tested concentrations to mitigate drought-induced damage in bean plants to obtain satisfactory growth and productivity under a water deficit of up to 40%.

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