scholarly journals Activation of the ABA Signal Pathway Mediated by GABA Improves the Drought Resistance of Apple Seedlings

2021 ◽  
Vol 22 (23) ◽  
pp. 12676
Author(s):  
Chenlu Liu ◽  
Hongtao Wang ◽  
Xiuzhi Zhang ◽  
Fengwang Ma ◽  
Tianli Guo ◽  
...  
Keyword(s):  
Drought Stress ◽  
Stomatal Conductance ◽  
Stomatal Closure ◽  
Carbon Dioxide Concentration ◽  
Closure Rate ◽  
Relative Water ◽  
Leaf Tissues ◽  
Mda Content ◽  
Relative Electrical Conductivity ◽  
Exogenous Treatment

Drought seriously affects the yield and quality of apples. γ-aminobutyric acid (GABA) plays an important role in the responses of plants to various stresses. However, the role and possible mechanism of GABA in the drought response of apple seedlings remain unknown. To explore the effect of GABA on apple seedlings under drought stress, seedlings of Malus hupehensis were treated with seven concentrations of GABA, and the response of seedlings under 15-day drought stress was observed. The results showed that 0.5 mM GABA was the most effective at relieving drought stress. Treatment with GABA reduced the relative electrical conductivity and MDA content of leaves induced by drought stress and significantly increased the relative water content of leaves. Exogenous GABA significantly decreased the stomatal conductance and intercellular carbon dioxide concentration and transpiration rate, and it significantly increased the photosynthetic rate under drought. GABA also reduced the accumulation of superoxide anions and hydrogen peroxide in leaf tissues under drought and increased the activities of POD, SOD, and CAT and the content of GABA. Exogenous treatment with GABA acted through the accumulation of abscisic acid (ABA) in the leaves to significantly decrease stomatal conductance and increase the stomatal closure rate, and the levels of expression of ABA-related genes PYL4, ABI1, ABI2, HAB1, ABF3, and OST1 changed in response to drought. Taken together, exogenous GABA can enhance the drought tolerance of apple seedlings.

scholarly journals Isolation, purification and characterization of an ascorbate peroxidase from celery and overexpression of the AgAPX1 gene enhanced ascorbate content and drought tolerance in Arabidopsis

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Jie-Xia Liu ◽  
Kai Feng ◽  
Ao-Qi Duan ◽  
Hui Li ◽  
Qing-Qing Yang ◽  
...  
Keyword(s):  
Drought Stress ◽  
Ascorbate Peroxidase ◽  
Drought Resistance ◽  
Stomatal Closure ◽  
High Survival ◽  
Gene Encoding ◽  
Sds Page ◽  
Relative Water ◽  
New Evidence

Abstract Background Celery is a widely cultivated vegetable abundant in ascorbate (AsA), a natural plant antioxidant capable of scavenging free radicals generated by abiotic stress in plants. Ascorbate peroxidase (APX) is a plant antioxidant enzyme that is important in the synthesis of AsA and scavenging of excess hydrogen peroxide. However, the characteristics and functions of APX in celery remain unclear to date. Results In this study, a gene encoding APX was cloned from celery and named AgAPX1. The transcription level of the AgAPX1 gene was significantly upregulated under drought stress. AgAPX1 was expressed in Escherichia coli BL21 (DE3) and purified. The predicted molecular mass of rAgAPX1 was 33.16 kDa, which was verified by SDS-PAGE assay. The optimum pH and temperature for rAgAPX1 were 7.0 and 55 °C, respectively. Transgenic Arabidopsis hosting the AgAPX1 gene showed elevated AsA content, antioxidant capacity and drought resistance. Less decrease in net photosynthetic rate, chlorophyll content, and relative water content contributed to the high survival rate of transgenic Arabidopsis lines after drought. Conclusions The characteristics of APX in celery were different from that in other species. The enhanced drought resistance of overexpressing AgAPX1 in Arabidopsis may be achieved by increasing the accumulation of AsA, enhancing the activities of various antioxidant enzymes, and promoting stomatal closure. Our work provides new evidence to understand APX and its response mechanisms to drought stress in celery.

scholarly journals Physiological responses of two halophytic grass species under drought stress environment

2016 ◽  
Vol 75 (1) ◽  
pp. 31-38 ◽  
Author(s):  
Zamin Shaheed Siddiqui ◽  
Huda Shahid ◽  
Jung-Il Cho ◽  
Sung-Han Park ◽  
Tae-Hun Ryu ◽  
...  
Keyword(s):  
Drought Stress ◽  
Stomatal Conductance ◽  
Water Deficit ◽  
Physiological Responses ◽  
Biomass Accumulation ◽  
Photosynthetic Performance ◽  
Grass Species ◽  
Free Proline ◽  
Relative Water ◽  
Halophytic Grasses

AbstractThe physiological responses of two halophytic grass species, Halopyrum mucronatum (L.) Staph. and Cenchrus ciliaris (L.), under drought stress were evaluated. Biomass accumulation, relative water content, free proline, H2O2content, stomatal conductance, photosynthetic performance and quantum yield (Fv/Fmratio) were studied. Under drought conditions, these halophytic plants expressed differential responses to water deficit. Stomatal conductance and free proline content were higher in H. mucronatum than in C. ciliaris, while H2O2content in H. mucronatum was substantially lower than in C. ciliaris. Performance index showed considerable sensitivity to a water deficit condition, more so in C. ciliaris than in H. mucronatum. Results were discussed in relation to comparative physiological performance and antioxidant enzymes activity of both halophytic grasses under drought stress.

scholarly journals 278 Gas Exchange and Water Relations of Diverse Tall Fescue Cultivars in Response to Drought Stress

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 490C-490
Author(s):  
Bingru Huang ◽  
Hongwen Gao
Keyword(s):  
Drought Stress ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Tall Fescue ◽  
Festuca Arundinacea ◽  
Stomatal Closure ◽  
Photochemical Efficiency ◽  
Physiological Factors ◽  
Relative Water

To investigate shoot physiological responses to drought stress of six tall fescue (Festuca arundinacea) cultivars representing several generations of turfgrass improvement, forage-type `Kentucky-31', turf-type `Phoenix', `Phoenix', and `Houndog V', and dwarf-type `Rebel Jr` and `Bonsai' were grown in well-watered or drying soil for 35 days in a greenhouse. Net photosynthetic rate (Pn), stomatal conductance (gs), transpiration rate (Tr), relative water content (RWC), and photochemical efficiency (Fv/Fm) declined during drought progression in all cultivars, but the time and the severity of reductions varied with cultivars and physiological factors. Pn, RWC, gs, and Tr decreased significantly for `Rebel Jr', `Bonsai', and `Phoenix' when soil water content declined to 20% after 9 days of treatment (DOT) and for `Falcon II', `Houndog V', and `Kentucky-31' when soil water content dropped to 10% at 15 DOT. A significant decrease in Fv/Fm was not observed in drought-stressed plants until 21 DOT for `Rebel Jr', `Bonsai', and `Phoenix' and 28 DOT for `Houndog V', `Kentucky-31', and `Falcon II'. The decline in Pn was due mostly to internal water deficit and stomatal closure under short-term or mild drought-stress conditions. After a prolonged period of drought (35 DOT), higher Pn in `Falcon II', `Houndog V', and `Kentucky-31' could be attributed to their higher Fv/Fm.

Leaf morphology, photochemistry and water status changes in resprouting Quercus ilex during drought

2005 ◽  
Vol 32 (2) ◽  
pp. 117 ◽  
Author(s):  
Karen Peña-Rojas ◽  
Xavier Aranda ◽  
Richard Joffre ◽  
Isabel Fleck
Keyword(s):  
Drought Stress ◽  
Quercus Ilex ◽  
Structural Characteristics ◽  
Water Status ◽  
Stomatal Closure ◽  
Severe Drought ◽  
Clear Cut ◽  
Leaf Mass Area ◽  
Relative Water ◽  
Moderate Drought

Functional and morphological (structural) characteristics of Quercus ilex L. leaves under drought stress were studied in the forest and in a nursery. We compared undisturbed individuals (controls) with resprouts emerging after clear-cut or excision. When soil water availability was high, gas-exchange was similar in resprouts and controls, despite higher midday leaf water potential, midday leaf hydration and relative water content (RWC). In moderate drought, stomatal closure was found to limit photosynthesis in controls, and in severe drought non-stomatal limitations of photosynthesis were also greater than in resprouts. Leaf structure and chemical composition changed under drought stress. Leaves tended to be smaller in controls with increasing drought, and resprouts had larger leaves and lower leaf mass area (LMA). The relationship between nitrogen (N) content and LMA implied lower N investment in photosynthetic components in controls, which could be responsible for their increased non-stomatal limitation of photosynthesis. Changes were more apparent in leaf density (D) and thickness (T), components of LMA. Decreases in D were related to reductions in cell wall components: hemicellulose, cellulose and lignin. In resprouts, reduced D and leaf T accounted for the higher mesophyll conductance (gmes) to CO2 measured.

scholarly journals Water relations and some aspects of leaf metabolism of Jatropha curcas young plants under two water deficit levels and recovery

2011 ◽  
Vol 23 (2) ◽  
pp. 123-130 ◽  
Author(s):  
Gabriela B. Arcoverde ◽  
Bruno M. Rodrigues ◽  
Marcelo F. Pompelli ◽  
Mauro G. Santos
Keyword(s):  
Drought Stress ◽  
Jatropha Curcas ◽  
Severe Drought ◽  
Mild Stress ◽  
Severe Stress ◽  
Sod Activity ◽  
Potted Plants ◽  
Relative Water ◽  
Mda Content ◽  
Main Barrier

Stomatal conductance (g s), transpiration (E), relative water content (RWC), superoxide dismutase activity (SOD), malondialdehyde (MDA), leaf carbohydrate soluble (LCS), free amino acids (FAA) and total protein (TP) content were measured under mild and severe drought stress in young potted Jatropha curcas L. in the greenhouse. The plants were kept for 12 days under three different water regimes, control (well hydrated), 50% irrigation control (mild stress) and 25% (severe stress), after rehydration were measured on the second and fourth day. Both mild and severe stress decreased g s and E; however, only severe stress reduced LCS, FAA and TP content and increased SOD activity (70%) and MDA content (60%) compared with the control. Moreover, under these conditions the plants showed severe leaf senescence. These results show that only severe drought stress decrease foliar metabolism in potted plants. These results show that severe drought decreased metabolism and leaf RWC, in potted plants. However, 48 h under a moderate stress is enough to drive the stomatal control is the main barrier against water loss. Finally, in the fourth day after rehydration the plants under a moderate and severe drought even had a g s and E reduced in both evaluation periods.

scholarly journals Biochemical and Molecular Effects Induced by Triacontanol in Acquired Tolerance of Rice to Drought Stress

Genes ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1119
Author(s):  
Basmah M. Alharbi ◽  
Awatif Mahfouz Abdulmajeed ◽  
Heba Hassan
Keyword(s):  
Drought Stress ◽  
Stomatal Conductance ◽  
Oryza Sativa L ◽  
Water Status ◽  
Stomatal Closure ◽  
Photochemical Efficiency ◽  
Seed Priming ◽  
Plant Tolerance ◽  
Photochemical Efficiency Of Psii ◽  
Aba Metabolism

To assess the effect of triacontanol (TRIA) on rice plants grown under normal or drought conditions, rice seeds were presoaked in TRIA (35 ppm) for two hours. After 20 days of sowing, rice seedlings developed from TRIA-treated or untreated seeds were subjected to drought stress. After 10 days of plant exposure to drought stress, data of major growth attributes and the content of photosynthetic pigments were recorded. Moreover, the effect of drought stress on stomatal conductance and the photochemical efficiency of PSII (Fv/Fm) were followed. The data obtained indicated that the species of rice (Oryza sativa L.) cultivar Giza 177 under investigation was sensitive to drought stress where there were significant decreases in the fresh and dry weights of shoots and roots and in stomatal conductance, as well as in the content of chlorophyll a, chlorophyll b, and carotenoids. Seed priming with TRIA enhanced both growth and acquired plant tolerance to drought stress. Thus, TRIA via the enhancement of stomatal conductance through the regulation of stomatal closure, the rate of water loss, ABA metabolism, the accumulation of osmolytes, and the regulation of aquaporins genes improved the water status of plants grown under water scarcity. Moreover, TRIA via increasing the content of free amino acids and sugars under drought stress may increase the chance of plant tissues to retain more water under scarcity conditions.

scholarly journals Mitigation of Drought Stress Effects on Pepper Seedlings by Exogenous Methylamine Application

2019 ◽  
Vol 76 ◽  
pp. 111-123
Author(s):  
Ertran Yildirim ◽  
Melek Ekinci ◽  
Raziye Kul ◽  
Metin Turan ◽  
Ayla Gür
Keyword(s):  
Drought Stress ◽  
Plant Growth ◽  
Dry Weight ◽  
Stress Effects ◽  
Shoot Dry Weight ◽  
New Synthesis ◽  
Relative Water ◽  
Mda Content ◽  
Irrigation Levels ◽  
Physiological And Biochemical

The study was conducted to determine effects of a new synthesis of methylamine on the plant growth, physiological and biochemical characteristics in pepper.  There were four irrigation levels [full irrigation (100%) (I0), 80% (I1), 60% (I2) and 40% (I3)] and two methylamine (MA) treatments (0, 2.5 mM). At the end of the study, it was observed that there were significant differences between applications and levels. Effects of MA treatments on plant growth (plant height, stem diameter, fresh, dry weight etc.), plant physiological and biochemical parameters [tissue electrical conductivity (TEC), tissue relative water content (TRWC), hydrogen peroxide (H2O2), malondialdehyde (MDA), proline, antioxidant enzyme activity], and plant nutrient element content of pepper seedlings under different irrigation levels were significantly important.  The results of the study showed that the drought stress conditions negatively affected the plant growth, increased the content of TEC, H2O2 and MDA, and decreased the TRWC and  plant mineral content in pepper. However, MA application improved plant growth and decreased TEC, H2O2 and MDA content compared to control in pepper under drought conditions. MA treated plants at I3 had higher shoot fresh weight and shoot dry weight than non-treated plants by 12 and 20%, respectively.  In conclusion, MA application could mitigate the deleterious effects of the drought stress on the pepper seedlings.

scholarly journals Water Relations of Well-watered Citrus Exposed to Cold-acclimating Temperatures

HortScience ◽  
2013 ◽  
Vol 48 (10) ◽  
pp. 1309-1312 ◽  
Author(s):  
Smita Barkataky ◽  
Robert C. Ebel ◽  
Kelly T. Morgan ◽  
Keri Dansereau
Keyword(s):  
Drought Stress ◽  
Cold Acclimation ◽  
Water Relations ◽  
Water Status ◽  
Stomatal Closure ◽  
Irrigation Scheduling ◽  
Stem Water Potential ◽  
Cold Temperatures ◽  
Relative Water ◽  
Leaf Relative Water Content

This study was conducted on well-watered citrus to determine changes in water relations during cold acclimation independent of drought stress. Potted sweet orange and Satsuma mandarin trees were exposed to progressively lower, non-freezing temperatures down to 10/4 °C, light/dark temperatures, respectively, for 9 weeks in environmental growth chambers to promote cold acclimation. The trees were watered twice daily and three times on the day water relations data were collected to minimize drought stress. Although soil moisture was higher and non-limiting for plants in the cold than in the warm chamber, cold temperatures promoted stomatal closure, higher root resistance, lower stem water potential (Ψstem), lower transpiration, and lower leaf ψS. Leaf relative water content (RWC) was not different for cold-acclimated trees compared with the controls. Cold acclimation promoted stomatal closure at levels only observed in severely drought-stressed plants exposed to warm temperatures and where Ψstem and RWC are typically much lower than what was found in this study. Ψstem continued to decline the last 4 weeks of the experiment although air temperature, leaf ψS, RWC, stomatal conductance (gS), and transpiration were constant. The results of this experiment indicate that water relations of citrus during cold acclimation vary from those known to occur as a result of drought stress, which have implications for using traditional measures of plant water status in irrigation scheduling during winter.

scholarly journals Regulatory networks of gene expression in maize (Zea mays) under drought stress and re-watering

2018 ◽  
Author(s):  
Liru Cao ◽  
Xiaomin Lu ◽  
Pengyu Zhang ◽  
Lixia Ku ◽  
Guorui Wang ◽  
...  
Keyword(s):  
Gene Expression ◽  
Superoxide Dismutase ◽  
Abscisic Acid ◽  
Drought Stress ◽  
Stomatal Conductance ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Proline Content ◽  
Relative Water ◽  
Leaf Relative Water Content

AbstractDrought can severely limit plant growth and production. However, few studies have investigated gene expression profiles in maize during drought/re-watering. We compared drought-treated and water-sufficient maize plants by measuring their leaf relative water content, superoxide dismutase and peroxidase activities, proline content, and leaf gas exchange parameters (photosynthetic rates, stomatal conductance, and transpiration rates). We conducted RNA sequencing analyses to elucidate gene expression profiles and identify miRNAs that might be related to drought resistance. A GO enrichment analysis showed that the common DEGs (differently expressed genes) between drought-treated and control plants were involved in response to stimulus, cellular process, metabolic process, cell part, and binding and catalytic activity. Analyses of gene expression profiles revealed that 26 of the DEGs under drought encoded 10 enzymes involved in proline synthesis, suggesting that increased proline synthesis was a key part of the drought response. We also investigated cell wall-related genes and transcription factors regulating abscisic acid-dependent and -independent pathways. The expression profiles of the miRNAs miR6214-3p, miR5072-3p, zma-miR529-5p, zma-miR167e-5p, zma-miR167f-5p, and zma-miR167j-5p and their relevant targets under drought conditions were analyzed. These results provide new insights into the molecular mechanisms of drought tolerance, and may identify new targets for breeding drought-tolerant maize lines.Abbreviationsleaf relative water content: RWC, superoxide dismutase activity: SOD, peroxidase activity: POD, proline content: Pro, photosynthetic rates: Pn, stomatal conductance: Cond, transpiration rates: Tr.; quantitative real-time polymerase chain reaction: qPCR; abscisic acid; ABA; polyethylene glycol :PEG; Principal component analysis :PCA; polyacrylamide gel electrophoresis :PAGEHighlightThe study of physiology and molecular mechanism of maize laid a theoretical foundation for drought resistance breeding under drought stress and re-watering.

RNAi mediated silencing of dehydrin gene WZY2 confers osmotic stress intolerance in transgenic wheat

2019 ◽  
Vol 46 (10) ◽  
pp. 877 ◽  
Author(s):  
Zhengyang Yu ◽  
Xin Wang ◽  
Xiaoqian Mu ◽  
Linsheng Zhang
Keyword(s):  
Osmotic Stress ◽  
Stomatal Closure ◽  
Transgenic Wheat ◽  
Wild Type ◽  
Osmotic Stress Tolerance ◽  
Relative Water ◽  
Mda Content ◽  
Related Enzyme ◽  
Dehydrin Gene ◽  
Indole 3 Acetic Acid

Dehydrins are involved in the prevention of osmotic damage in plants. Many studies have shown that overexpression of dehydrin genes can enhance the osmotic stress tolerance in transgenic plants. Our previous studies showed a YnSKn-type dehydrin gene WZY2 could be induced by polyethylene glycol (PEG), cold, indole-3-acetic acid (IAA), salicylic acid (SA) and abscisic acid (ABA). In the present study, we examined the phenotype and physiological indices in a dehydrin gene WZY2 RNA interference (RNAi) lines in wheat. Real-time PCR indicated a depressed WZY2 gene expression in transformed wheat. Furthermore, transgenic wheat showed lower relative water content, oxidative-related enzyme activities and higher malondialdehyde (MDA) content than wild-type bread wheat (Zhengyin No.1) under osmotic stress. Overexpression of the WZY2 in Arabidopsis thaliana (L.) Heynh. revealed a significant increase in tolerance to drought stress. Further studies also showed that WZY2 could participate in ABA-induced stomatal closure. These results demonstrated a key function of WZY2 in plant response to osmotic stress.

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