Physiological regulation of high transpiration efficiency in winter wheat under drought conditions

Pot experiments were conducted to study the variation and physiological regulation of transpiration efficiency (TE) of four winter wheat (Triticum aestivum L.) varieties that are widely grown in different ecological regions in North China. Plants were grown under two soil moisture regimes, normal and drought stress. The results showed that under drought stress condition, both TE at plant level and TE at leaf level (TEl) increased significantly. The transpiration rate (Tr) was reduced more strongly than leaf net CO<sub>2</sub> assimilation rate (Pn). The decline of Tr was mainly affected by stomatal conductance and the decline of Pn was affected by non-stomatal factors, which was confirmed by the decline in net photosynthetic oxygen evolution rate. The leaf soluble sugar content and proline content were significantly increased under drought stress. The stomatal density was increased and the stomatal length was reduced. These results led us to make the following conclusions: (1) Under drought stress, the increase in TEl appears to be regulated in two ways: via the stomata by regulating Tr, and independent of the stomata through regulation of Pn; regulation via the stomata was more sensitive; (2) Osmotic adjustment was closely correlated to the non-stomatal regulation, and stomatal aperture was closely correlated to the stomatal way.

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Nucleoredoxin Gene TaNRX1 Positively Regulates Drought Tolerance in Transgenic Wheat (Triticum aestivum L.)

Frontiers in Plant Science ◽

10.3389/fpls.2021.756338 ◽

2021 ◽

Vol 12 ◽

Author(s):

Yunrui Zhang ◽

Jianfei Zhou ◽

Fan Wei ◽

Tianqi Song ◽

Yang Yu ◽

...

Keyword(s):

Triticum Aestivum ◽

Drought Stress ◽

Stress Tolerance ◽

Sugar Content ◽

Soluble Sugar ◽

Triticum Aestivum L ◽

Growth And Yield ◽

Regulation Mechanism ◽

Drought Stress Tolerance ◽

Relative Electrical Conductivity

Drought is the main abiotic stress factor limiting the growth and yield of wheat (Triticum aestivum L.). Therefore, improving wheat tolerance to drought stress is essential for maintaining yield. Previous studies have reported on the important role of TaNRX1 in conferring drought stress tolerance. Therefore, to elucidate the regulation mechanism by which TaNRX1 confers drought resistance in wheat, we generated TaNRX1 overexpression (OE) and RNA interference (RNAi) wheat lines. The results showed that the tolerance of the OE lines to drought stress were significantly enhanced. The survival rate, leaf chlorophyll, proline, soluble sugar content, and activities of the antioxidant enzymes (catalase, superoxide dismutase, and peroxidase) of the OE lines were higher than those of the wild type (WT); however, the relative electrical conductivity and malondialdehyde, hydrogen peroxide, and superoxide anion levels of the OE lines were lower than those of the WT; the RNAi lines showed the opposite results. RNA-seq results showed that the common differentially expressed genes of TaNRX1 OE and RNAi lines, before and after drought stress, were mainly distributed in the plant–pathogen interaction, plant hormone signal transduction, phenylpropane biosynthesis, starch and sucrose metabolism, and carbon metabolism pathways and were related to the transcription factors, including WRKY, MYB, and bHLH families. This study suggests that TaNRX1 positively regulates drought stress tolerance in wheat.

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Morphological, Physiological and Biochemical Responses of Poplar Plants to Drought Stress

Journal of AgriSearch ◽

10.21921/jas.5.3.7 ◽

2018 ◽

Vol 5 (03) ◽

Author(s):

ARADHNA KUMARI ◽

IM KHAN ◽

ANIL KUMAR SINGH ◽

SANTOSH KUMAR SINGH

Keyword(s):

Water Stress ◽

Drought Stress ◽

Biochemical Parameters ◽

Sugar Content ◽

Soluble Sugar ◽

Field Capacity ◽

Drought Event ◽

Total Biomass ◽

Biochemical Responses ◽

Physiological And Biochemical

Poplar clone Kranti was selected to assess the morphological, physiological and biochemical responses under drought at different levels of water stress, as it is a common clone used to be grown in Uttarakhand for making paper and plywood. The cuttings of Populus deltoides L. (clone Kranti) were exposed to four different watering regimes (100, 75, 50 and 25% of the field capacity) and changes in physiological and biochemical parameters related with drought tolerance were recorded. Alterations in physiological (i.e. decrease in relative water content) and biochemical parameters (i.e. increase in proline and soluble sugar content and build-up of malondialdehyde by-products) occurred in all the three levels of water stress, although drought represented the major determinant. Drought treatments (75%, 50% and 25% FC) decreased plant height, radial stem diameter, harvest index, total biomass content and RWC in all the three watering regimes compared to control (100% FC). Biochemical parameters like proline, soluble sugar and MDA content increased with severity and duration of stress, which helped plants to survive under severe stress. It was analyzed that for better wood yield poplar seedlings should avail either optimum amount of water (amount nearly equal to field capacity of soil) or maximum withdrawal up to 75% of field capacity up to seedling establishment period (60 days). Furthermore, this study manifested that acclimation to drought stress is related with the rapidity, severity, and duration of the drought event of the poplar species.

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Yield component variation in winter wheat grown under drought stress

Canadian Journal of Plant Science ◽

10.4141/p00-006 ◽

2000 ◽

Vol 80 (4) ◽

pp. 739-745 ◽

Cited By ~ 33

Author(s):

B. L. Duggan ◽

D. R. Domitruk ◽

D. B. Fowler

Keyword(s):

Drought Stress ◽

Winter Wheat ◽

Grain Yield ◽

Triticum Aestivum L ◽

Yield Component ◽

Yield Potential ◽

High Yield ◽

Crop Water ◽

Kernel Number ◽

High Yield Potential

Crops produced in the semiarid environment of western Canada are subjected to variable and unpredictable periods of drought stress. The objective of this study was to determine the inter-relationships among yield components and grain yield of winter wheat (Triticum aestivum L) so that guidelines could be established for the production of cultivars with high yield potential and stability. Five hard red winter wheat genotypes were grown in 15 field trials conducted throughout Saskatchewan from 1989–1991. Although this study included genotypes with widely different yield potential and yield component arrangements, only small differences in grain yield occurred within trials under dryland conditions. High kernel number, through greater tillering, was shown to be an adaptation to low-stress conditions. The ability of winter wheat to produce large numbers of tillers was evident in the spring in all trials; however, this early season potential was not maintained due to extensive tiller die-back. Tiller die-back often meant that high yield potential genotypes became sink limiting with reduced ability to respond to subsequent improvements in growing season weather conditions. As tiller number increased under more favourable crop water conditions genetic limits in kernels spike−1 became more identified with yield potential. It is likely then, that tillering capacity per se is less important in winter wheat than the development of vigorous tillers with numerous large kernels spike−1. For example, the highest yielding genotype under dryland conditions was a breeding line, S86-808, which was able to maintain a greater sink capacity as a result of a higher number of larger kernels spike−1. It appears that without yield component compensation, a cultivar can be unresponsive to improved crop water conditions (stable) or it can have a high mean yield, but it cannot possess both characteristics. Key words: Triticum aestivum L., wheat, drought stress, kernel weight, kernel number, spike density, grain yield

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Exogenous Melatonin Modulates the Physiological and Biochemical Mechanisms of Drought Tolerance in Tartary Buckwheat (Fagopyrum tataricum (L.) Gaertn)

Molecules ◽

10.3390/molecules25122828 ◽

2020 ◽

Vol 25 (12) ◽

pp. 2828

Author(s):

Md. Shakhawat Hossain ◽

Jing Li ◽

Ashim Sikdar ◽

Mirza Hasanuzzaman ◽

Ferdinand Uzizerimana ◽

...

Keyword(s):

Drought Stress ◽

Plant Growth ◽

Sugar Content ◽

Soluble Sugar ◽

Growth And Yield ◽

Tartary Buckwheat ◽

Arid Zones ◽

Enzymatic Antioxidants ◽

Fagopyrum Tataricum ◽

Exogenous Melatonin

Tartary buckwheat is one of the nutritious minor cereals and is grown in high-cold mountainous areas of arid and semi-arid zones where drought is a common phenomenon, potentially reducing the growth and yield. Melatonin, which is an amphiphilic low molecular weight compound, has been proven to exert significant effects in plants, under abiotic stresses, but its role in the Tartary buckwheat under drought stress remains unexplored. We evaluated the influence of melatonin supplementation on plant morphology and different physiological activities, to enhance tolerance to posed drought stress by scavenging reactive oxygen species (ROS) and alleviating lipid peroxidation. Drought stress decreased the plant growth and biomass production compared to the control. Drought also decreased Chl a, b, and the Fv/Fm ratio by 54%, 70%, and 8%, respectively, which was associated with the disorganized stomatal properties. Under drought stress, H2O2, O2•−, and malondialdehyde (MDA) contents increased by 2.30, 2.43, and 2.22-folds, respectively, which caused oxidative stress. In contrast, proline and soluble sugar content were increased by 84% and 39%, respectively. However, exogenous melatonin (100 µM) could improve plant growth by preventing ROS-induced oxidative damage by increasing photosynthesis, enzymatic antioxidants (superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase), secondary metabolites like phenylalanine ammonialyase, phenolics, and flavonoids, total antioxidant scavenging (free radical DPPH scavenging), and maintaining relative water content and osmoregulation substances under water stress. Therefore, our study suggested that exogenous melatonin could accelerate drought resistance by enhancing photosynthesis and antioxidant defense in Tartary buckwheat plants.

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Genetic determination of stomatal patterning in winter wheat (Triticum aestivum L.)

10.1101/490029 ◽

2018 ◽

Author(s):

Steven Andrew Yates ◽

Andreas Bruun ◽

Marius Hodel ◽

Christoph Grieder ◽

Andreas Hund ◽

...

Keyword(s):

Triticum Aestivum ◽

Winter Wheat ◽

Stomatal Density ◽

Crop Improvement ◽

Genotypic Variation ◽

Triticum Aestivum L ◽

Auxin Signaling ◽

Genetic Determination ◽

Wheat Germplasm ◽

Stomatal Patterning

Leaf stomata are microscopic pores mediating plant-environment interactions. Their role in carbon uptake and transpiration make them prime candidates for improving water use efficiency (WUE). Stomatal density (SD), the number of stomata per unit area, has been shown to be negatively correlated with WUE. However, little is known about the genetic basis of SD in wheat (Triticum aestivum L.), and to what extant genetic variation exists in contemporary wheat germplasm. Here, we evaluated stomatal patterning over two growing seasons in a set of 333 wheat lines, representing the European winter wheat germplasm. Stomatal patterning was mainly determined by two underlying traits, the distance between files of stomata and the distance between stomata within a file. By haplotype association mapping, quantitative trait loci for SD were consistently detected in both seasons on wheat chromosomes (CHR) 2A, 3A and 7B. The single nucleotide polymorphism markers most significantly associated with SD coincided with the genes INDUCER OF CBF EXPRESSION 1 (ICE1) and STOMATAL CYTOKINESIS-DEFECTIVE 1 (SCD1) on CHR 3A, and genes involved in ethylene and auxin signaling on CHR 2A and 7B, respectively. Our study unlocks the phenotypic and genotypic variation for stomatal patterning traits in contemporary wheat germplasm. It provides gene targets for functional validation and practical tools to manipulate SD using marker-assisted selection for crop improvement.

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Synergistic effects of abscisic acid (ABA) and drought stress on the physiological responses of winter wheat (Triticum aestivum L.)

Pakistan Journal of Botany ◽

10.30848/pjb2021-5(11) ◽

2021 ◽

Vol 53 (5) ◽

Author(s):

Haiyan Kong ◽

Zhen Zhang ◽

Juan Qin ◽

Nudrat Aisha Akram

Keyword(s):

Triticum Aestivum ◽

Abscisic Acid ◽

Drought Stress ◽

Winter Wheat ◽

Synergistic Effects ◽

Physiological Responses ◽

Triticum Aestivum L

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EFFECT OF DROUGHT ON FROST RESISTANCE AND FATTY ACID CONTENT OF YOUNG WINTER WHEAT PLANTS

Canadian Journal of Plant Science ◽

10.4141/cjps79-101 ◽

1979 ◽

Vol 59 (3) ◽

pp. 639-643 ◽

Cited By ~ 22

Author(s):

C. WILLEMOT ◽

L. PELLETIER

Keyword(s):

Drought Stress ◽

Winter Wheat ◽

Frost Resistance ◽

Fatty Acid Content ◽

Triticum Aestivum L ◽

Temperature Treatment ◽

Frost Hardening ◽

Low Temperature Treatment ◽

Degree Of Unsaturation ◽

Water Holding

Low soil moisture, both prior to and during freezing, increased frost resistance of 12-day-old winter wheat (Triticum aestivum L.) plants. While frost resistance increased, percentage of linolenic acid decreased in drought-stressed plants (10% of soil water-holding capacity) as compared with controls (40%). This occurred whether drought stress was applied before freezing at 1 °C or at 20 °C. A degree of frost hardening can be achieved in winter wheat by drought stress without low temperature treatment, and without an increase in degree of unsaturation of fatty acids.

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Antecedent Drought Condition Affects Responses of Plant Physiology and Growth to Drought and Post-drought Recovery

Frontiers in Forests and Global Change ◽

10.3389/ffgc.2021.704470 ◽

2021 ◽

Vol 4 ◽

Author(s):

Ximeng Li ◽

Jingting Bao ◽

Jin Wang ◽

Chris Blackman ◽

David Tissue

Keyword(s):

Plant Physiology ◽

Water Stress ◽

Drought Stress ◽

Stomatal Conductance ◽

Sugar Content ◽

Soluble Sugar ◽

Severe Drought ◽

Substantial Impact ◽

Drought Recovery ◽

Water Limitations

Antecedent environmental conditions may have a substantial impact on plant response to drought and recovery dynamics. Saplings of Eucalyptus camaldulensis were exposed to a range of long-term water deficit pre-treatments (antecedent conditions) designed to reduce carbon assimilation to approximately 50 (A50) and 10% (A10) of maximum photosynthesis of well-watered plants (A100). Thereafter, water was withheld from all plants to generate three different levels of water stress before re-watering. Our objective was to assess the role of antecedent water limitations in plant physiology and growth recovery from mild to severe drought stress. Antecedent water limitations led to increased soluble sugar content and depletion of starch in leaves of A50 and A10 trees, but there was no significant change in total non-structural carbohydrate concentration (NSC; soluble sugar and starch), relative to A100 plants. Following re-watering, A50 and A10 trees exhibited faster recovery of physiological processes (e.g., photosynthesis and stomatal conductance) than A100 plants. Nonetheless, trees exposed to the greatest water stress (−5.0 MPa) were slowest to fully recover photosynthesis (Amax) and stomatal conductance (gs). Moreover, post-drought recovery of photosynthesis was primarily limited by gs, but was facilitated by biochemistry (Vcmax and Jmax). During recovery, slow regrowth rates in A50 and A10 trees may result from insufficient carbon reserves as well as impaired hydraulic transport induced by the antecedent water limitations, which was dependent on the intensity of drought stress. Therefore, our findings suggest that antecedent water stress conditions, as well as drought severity, are important determinants of physiological recovery following drought release.

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Effect of exogenous alpha-tocopherol on physio-biochemical attributes and agronomic performance of lentil (Lens culinaris Medik.) under drought stress

PLoS ONE ◽

10.1371/journal.pone.0248200 ◽

2021 ◽

Vol 16 (8) ◽

pp. e0248200

Author(s):

Wadood Shah ◽

Sami Ullah ◽

Sajjad Ali ◽

Muhammad Idrees ◽

Muhammad Nauman Khan ◽

...

Keyword(s):

Lipid Peroxidation ◽

Growth Rate ◽

Drought Stress ◽

Leaf Area ◽

Glycine Betaine ◽

Sugar Content ◽

Soluble Sugar ◽

Stress Conditions ◽

Area Index ◽

Induced Stress

Water being a vital part of cell protoplasm plays a significant role in sustaining life on earth; however, drastic changes in climatic conditions lead to limiting the availability of water and causing other environmental adversities. α-tocopherol being a powerful antioxidant, protects lipid membranes from the drastic effects of oxidative stress by deactivating singlet oxygen, reducing superoxide radicals, and terminating lipid peroxidation by reducing fatty acyl peroxy radicals under drought stress conditions. A pot experiment was conducted and two groups of lentil cultivar (Punjab-2009) were exposed to 20 and 25 days of drought induced stress by restricting the availability of water after 60th day of germination. Both of the groups were sprinkled with α-tocopherol 100, 200 and 300 mg/L. Induced water deficit stress conditions caused a pronounced decline in growth parameters including absolute growth rate (AGR), leaf area index (LAI), leaf area ratio (LAR), root shoot ratio (RSR), relative growth rate (RGR), chlorophyll a, b, total chlorophyll content, carotenoids, and soluble protein content (SPC) which were significantly enhanced by exogenously applied α-tocopherol. Moreover, a significant increase was reported in total proline content (TPC), soluble sugar content (SSC), glycine betaine (GB) content, endogenous tocopherol levels, ascorbate peroxidase (APX), catalase (CAT) peroxidase (POD) and superoxide dismutase (SOD) activities. On the contrary, exogenously applied α-tocopherol significantly reduced the concentrations of malondialdehyde (MDA) and hydrogen peroxide (H2O2). In conclusion, it was confirmed that exogenous application of α-tocopherol under drought induced stress regimes resulted in membrane protection by inhibiting lipid peroxidation, enhancing the activities of antioxidative enzymes (APX, CAT, POD, and SOD) and accumulation of osmolytes such as glycine betaine, proline and sugar. Consequently, modulating different growth, physiological and biochemical attributes.

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