DIFFERENTIAL RESPONSE OF WHEAT GENOTYPES TO HEAT STRESS DURING GRAIN FILLING

SUMMARYClimatic change affects global agriculture and is a severe threat to global food security due to variability of the three factors measuring climate change (CO2, temperature and precipitation) with temperature being the most crucial one. Wheat is severely affected by high temperatures with reproductive and grain-filling phases being most sensitive, impacting grain number, size and weight. Seed size and weight are the key agronomic traits subjected to artificial selection and involved in the domestication process since the origin of agriculture. Three genotypes Banks, EGA Gregory and Fang-60 with the latter known to be heat tolerant were grown under glass house conditions and subjected to heat stress for 3 days during early- (11–14 dpa – days post anthesis) and late- (27–30 dpa) grain filling stages in a mutually exclusive fashion. The impact of heat stress during early- and late- grain filling on the four major grain characteristics, thousand grain weight (TGW), grain length, grain width and grain thickness was assessed. The tolerant genotype Fang-60 exhibited significantly higher TGW during early-grain filling heat stress than the control possibly due to an ability to exploit the accelerated release of fertilizer under high temperature. Banks and EGA Gregory were moderately tolerant to susceptible to heat stress, respectively, at early- and late-grain filling with Fang-60 being tolerant to both early- and late- grain filling heat stress. This study confirms the availability of significant genetic variation in heat stress response in wheat that might be exploited to adapt wheat to higher growth temperatures.

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Evaluation of Triticum durum–Aegilops tauschii derived primary synthetics as potential sources of heat stress tolerance for wheat improvement

Plant Genetic Resources ◽

10.1017/s1479262121000113 ◽

2021 ◽

Vol 19 (1) ◽

pp. 74-89

Author(s):

Amandeep Kaur ◽

Parveen Chhuneja ◽

Puja Srivastava ◽

Kuldeep Singh ◽

Satinder Kaur

Keyword(s):

Heat Stress ◽

Stress Tolerance ◽

Hexaploid Wheat ◽

Aegilops Tauschii ◽

Grain Filling ◽

World Population ◽

Potential Candidate ◽

Terminal Heat Stress ◽

Heat Stress Tolerance ◽

The Impact

AbstractAddressing the impact of heat stress during flowering and grain filling is critical to sustaining wheat productivity to meet a steadily increasing demand from a rapidly growing world population. Crop wild progenitor species of wheat possess a wealth of genetic diversity for several biotic and abiotic stresses, and morphological traits and can serve as valuable donors. The transfer of useful variation from the diploid progenitor, Aegilops tauschii, to hexaploid wheat can be done through the generation of synthetic hexaploid wheat (SHW). The present study targeted the identification of potential primary SHWs to introduce new genetic variability for heat stress tolerance. Selected SHWs were screened for different yield-associated traits along with three advanced breeding lines and durum parents as checks for assessing terminal heat stress tolerance under timely and late sown conditions for two consecutive seasons. Heat tolerance index based on the number of productive tillers and thousand grain weight indicated that three synthetics, syn9809 (64.32, 78.80), syn14128 (50.30, 78.28) and syn14135 (58.16, 76.03), were able to endure terminal heat stress better than other SHWs as well as checks. One of these synthetics, syn14128, recorded a minimum reduction in thousand kernel weight (21%), chlorophyll content (2.56%), grain width (1.07%) despite minimum grain-filling duration (36.15 d) and has been selected as a potential candidate for introducing the terminal heat stress tolerance in wheat breeding programmes. Breeding efforts using these candidate donors will help develop lines with a higher potential to express the desired heat stress-tolerant phenotype under field conditions.

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Heat stress in grain legumes during reproductive and grain-filling phases

Crop and Pasture Science ◽

10.1071/cp17012 ◽

2017 ◽

Vol 68 (11) ◽

pp. 985 ◽

Cited By ~ 18

Author(s):

Muhammad Farooq ◽

Faisal Nadeem ◽

Nirmali Gogoi ◽

Aman Ullah ◽

Salem S. Alghamdi ◽

...

Keyword(s):

Heat Stress ◽

High Temperature ◽

Grain Yield ◽

Leaf Senescence ◽

Management Strategies ◽

Substantial Reduction ◽

Grain Filling ◽

Grain Legumes ◽

Grain Legume ◽

The Impact

Thermal stress during reproductive development and grain-filling phases is a serious threat to the quality and productivity of grain legumes. The optimum temperature range for grain legume crops is 10−36°C, above which severe losses in grain yield can occur. Various climatic models have simulated that the temperature near the earth’s surface will increase (by up to 4°C) by the end of this century, which will intensify the chances of heat stress in crop plants. The magnitude of damage or injury posed by a high-temperature stress mainly depends on the defence response of the crop and the specific growth stage of the crop at the time of exposure to the high temperature. Heat stress affects grain development in grain legumes because it disintegrates the tapetum layer, which reduces nutrient supply to microspores leading to premature anther dehiscence; hampers the synthesis and distribution of carbohydrates to grain, curtailing the grain-filling duration leading to low grain weight; induces poor pod development and fractured embryos; all of which ultimately reduce grain yield. The most prominent effects of heat stress include a substantial reduction in net photosynthetic rate, disintegration of photosynthetic apparatus and increased leaf senescence. To curb the catastrophic effect of heat stress, it is important to improve heat tolerance in grain legumes through improved breeding and genetic engineering tools and crop management strategies. In this review, we discuss the impact of heat stress on leaf senescence, photosynthetic machinery, assimilate translocation, water relations, grain quality and development processes. Furthermore, innovative breeding, genetic, molecular and management strategies are discussed to improve the tolerance against heat stress in grain legumes.

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Quantifying the Impact of Heat Stress on Pollen Germination, Seed Set, and Grain Filling in Spring Wheat

Crop Science ◽

10.2135/cropsci2018.05.0292 ◽

2019 ◽

Vol 59 (2) ◽

pp. 684-696 ◽

Cited By ~ 10

Author(s):

Raju Bheemanahalli ◽

V. S. John Sunoj ◽

Gautam Saripalli ◽

P. V. Vara Prasad ◽

H. S. Balyan ◽

...

Keyword(s):

Heat Stress ◽

Spring Wheat ◽

Pollen Germination ◽

Seed Set ◽

Grain Filling ◽

The Impact

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Regulation of DNA (de)Methylation Positively Impacts Seed Germination during Seed Development under Heat Stress

Genes ◽

10.3390/genes12030457 ◽

2021 ◽

Vol 12 (3) ◽

pp. 457

Author(s):

Jaiana Malabarba ◽

David Windels ◽

Wenjia Xu ◽

Jerome Verdier

Keyword(s):

Gene Expression ◽

Heat Stress ◽

Seed Germination ◽

Seed Development ◽

Molecular Mechanisms ◽

Dna Demethylation ◽

Mild Stress ◽

Germination Capacity ◽

Heat Stress Response ◽

The Impact

Seed development needs the coordination of multiple molecular mechanisms to promote correct tissue development, seed filling, and the acquisition of germination capacity, desiccation tolerance, longevity, and dormancy. Heat stress can negatively impact these processes and upon the increase of global mean temperatures, global food security is threatened. Here, we explored the impact of heat stress on seed physiology, morphology, gene expression, and methylation on three stages of seed development. Notably, Arabidopsis Col-0 plants under heat stress presented a decrease in germination capacity as well as a decrease in longevity. We observed that upon mild stress, gene expression and DNA methylation were moderately affected. Nevertheless, upon severe heat stress during seed development, gene expression was intensively modified, promoting heat stress response mechanisms including the activation of the ABA pathway. By analyzing candidate epigenetic markers using the mutants’ physiological assays, we observed that the lack of DNA demethylation by the ROS1 gene impaired seed germination by affecting germination-related gene expression. On the other hand, we also observed that upon severe stress, a large proportion of differentially methylated regions (DMRs) were located in the promoters and gene sequences of germination-related genes. To conclude, our results indicate that DNA (de)methylation could be a key regulatory process to ensure proper seed germination of seeds produced under heat stress.

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A Heat Stress Responsive NAC Transcription Factor Heterodimer Plays Key Roles in Rice Grain Filling

Journal of Experimental Botany ◽

10.1093/jxb/erab027 ◽

2021 ◽

Author(s):

Ye Ren ◽

Zhouquan Huang ◽

Hao Jiang ◽

Zhuo Wang ◽

Fengsheng Wu ◽

...

Keyword(s):

Transcription Factors ◽

Heat Stress ◽

Stress Responses ◽

Transcriptional Regulatory Network ◽

Grain Filling ◽

Rice Grain ◽

Knock Out ◽

Heat Stress Response ◽

Monosaccharide Transporter ◽

Stimulus Response

Abstract High temperature often leads to the failure of grain filling in rice (Oryza sativa) to cause yield loss, while the mechanism is not well elucidated yet. Here, we report that two seed-specific NAM/ATAF/CUC domain transcription factors, ONAC127 and ONAC129, are responsive to heat stress and involved in the grain filling process of rice. ONAC127 and ONAC129 are dominantly expressed in the pericarp and can form a heterodimer during rice grain filling. CRISPR/Cas9 induced mutants and overexpression lines were then generated to investigate the functions of these two transcription factors. Interestingly, both knock-out and overexpression plants showed incomplete grain filling and shrunken grains, which became more severe under heat stress. Transcriptome analysis revealed that ONAC127 and ONAC129 mainly regulate stimulus response and nutrient transport. ChIP-seq analysis identified that the direct targets of ONAC127 and ONAC129 in developing rice seeds include monosaccharide transporter OsMST6, sugar transporter OsSWEET4, calmodulin-like protein OsMSR2 and AP2/ERF factor OsEATB. These results suggest that ONAC127 and ONAC129 may regulate grain filling through affecting sugar transportation and abiotic stress responses. Overall, this study demonstrates a transcriptional regulatory network involving ONAC127 and ONAC129 and coordinating multiple pathways to modulate seed development and heat stress response at rice reproductive stage.

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Regulation of DNA (de)methylation positively impacts seed germination during seed development under heat stress

10.1101/2021.02.25.432822 ◽

2021 ◽

Author(s):

Jaiana Malabarba ◽

David Windels ◽

Wenjia Xu ◽

Jerome Verdier

Keyword(s):

Gene Expression ◽

Heat Stress ◽

Seed Germination ◽

Seed Development ◽

Molecular Mechanisms ◽

Dna Demethylation ◽

Mild Stress ◽

Germination Capacity ◽

Heat Stress Response ◽

The Impact

AbstractSeed development needs the coordination of multiple molecular mechanisms to promote correct tissue development, seed filling and the acquisition of germination capacity, desiccation tolerance, longevity and dormancy. Heat stress can negatively impact these processes and upon the increasing of global mean temperatures, global food security is threatened. Here, we explored the impact of heat stress on seed physiology, morphology, gene expression and methylation on three stages of seed development. Notably, Arabidopsis Col-0 plants under heat stress presented a decrease in germination capacity and also a decrease in longevity. We observed that upon mild stress, gene expression and DNA methylation were moderately affected. Nevertheless, upon severe heat stress during seed development, gene expression was intensively modified, promoting heat stress response mechanisms, including the activation of ABA pathway. By analyzing candidate epigenetic marks using mutants’ physiological assays, we observed that the lack of DNA demethylation by ROS1 gene impaired seed germination by affecting germination-related genes expression. On the other hand, we also observed that upon severe stress, a large proportion of differentially methylated regions (DMRs) were located in promoters and gene sequences of germination-related genes. To conclude, our results indicate that DNA (de)methylation could be a key regulatory process to ensure proper seed germination of seeds produced under heat stress.Graphic Abstract

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Increasing Heat Tolerance in Wheat to Counteract Recent and Projected Increases in Heat Stress

Proceedings ◽

10.3390/proceedings2019036132 ◽

2020 ◽

Vol 36 (1) ◽

pp. 132

Author(s):

Najeeb Ullah ◽

Behnam Ababaei ◽

Karine Chenu

Keyword(s):

Grain Size ◽

Heat Stress ◽

Leaf Senescence ◽

Recombinant Inbred Lines ◽

Grain Filling ◽

Heat Effects ◽

Heat Shocks ◽

Tolerant Line ◽

The Impact ◽

Leaf Greenness

The frequency of heat shocks during grain filling of wheat crops across the Australian wheatbelt has significantly increased over the last 30 years. These post-flowering heat events significantly reduce wheat yields with a relatively greater impact on grain size than grain number. A controlled environment study was conducted to assess the impact of post-flowering heat shocks on wheat recombinant inbred lines SB062 and SB003. Plants were submitted to 7-day heat shocks (33/21 °C day/night temperature) at different periods during grain filling. Heat shocks significantly accelerated leaf senescence, with a greater impact on older leaves and for mid post-flowering stresses. Overall, the tolerant line (SB062) could maintain leaf greenness longer than the sensitive line (SB003), especially when submitted to heat stress. Further, heat shocks during early-to-mid grain filling reduced the grain size and weight. While the impact on developing grains was significant in SB003, no significant effect of post-flowering heat was observed on leaf senescence nor on grain size in the tolerant line SB062. Delayed leaf senescence appeared to play a role in maintaining grain size under heat stress. The research findings will assist improving crop models for post-flowering heat effects and developing techniques for screening heat tolerant wheat lines. Increased post-flowering assimilate production through sustained leaf greenness could improve the performance of wheat crops in increasingly warmer environments.

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A Heat Stress Responsive NAC Transcription Factor Heterodimer Plays Key Roles in Rice Grain Filling

10.1101/2020.02.08.939728 ◽

2020 ◽

Author(s):

Ye Ren ◽

Zhouquan Huang ◽

Hao Jiang ◽

Zhuo Wang ◽

Fengsheng Wu ◽

...

Keyword(s):

Transcription Factor ◽

Transcription Factors ◽

Heat Stress ◽

Stress Response ◽

Stress Responses ◽

Transcriptional Regulatory Network ◽

Grain Filling ◽

Nac Transcription Factor ◽

Rice Grain ◽

Heat Stress Response

AbstractHigh temperature often leads to the failure of grain filling in rice (Oryza sativa) to cause yield loss, while the mechanism is not well elucidated yet. Here, we report that two seed-specific NAM/ATAF/CUC domain transcription factors, ONAC127 and ONAC129, are responsive to heat stress and involved in the grain filling process of rice. ONAC127 and ONAC129 are dominantly expressed in the pericarp and can form a heterodimer during rice grain filling. CRISPR/Cas9 induced mutants and overexpression lines were then generated to investigate the functions of these two transcription factors. Interestingly, both knock-out and overexpression plants showed incomplete grain filling and shrunken grains, which became more severe under heat stress. Transcriptome analysis revealed that ONAC127 and ONAC129 mainly regulate stimulus response and nutrient transport. ChIP-seq analysis identified that the direct targets of ONAC127 and ONAC129 in developing rice seeds include monosaccharide transporter OsMST6, sugar transporter OsSWEET4, calmodulin-like protein OsMSR2 and AP2/ERF factor OsEATB. These results suggest that ONAC127 and ONAC129 may regulate grain filling through affecting sugar transportation and abiotic stress responses. Overall, this study demonstrates a transcriptional regulatory network involving ONAC127 and ONAC129 and coordinating multiple pathways to modulate seed development and heat stress response at rice reproductive stage.HighlightA NAC transcription factor heterodimer plays vital roles in heat stress response and sugar transportation at rice grain filling stage.

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