Heat Stress Tolerance In Wheat Research Articles

Exploring the Role of TaPLC1-2B in Heat Tolerance at Seedling and Adult Stages of Wheat through Transcriptome Analysis

Heat stress is a major abiotic stress that can cause serious losses of a crop. Our previous work identified a gene involved in heat stress tolerance in wheat, TaPLC1-2B. To further investigate its mechanisms, in the present study, TaPLC1-2B RNAi-silenced transgenic wheat and the wild type were comparatively analyzed at both the seedling and adult stages, with or without heat stress, using transcriptome sequencing. A total of 15,549 differentially expressed genes (DEGs) were identified at the adult stage and 20,535 DEGs were detected at the seedling stage. After heat stress, an enrichment of pathways such as phytohormones and mitogen-activated protein kinase signaling was mainly found in the seedling stage, and pathways related to metabolism, glycerophospholipid metabolism, circadian rhythms, and ABC transporter were enriched in the adult stage. Auxin and abscisic acid were downregulated in the seedling stage and vice versa in the adult stage; and the MYB, WRKY, and no apical meristem gene families were downregulated in the seedling stage in response to heat stress and upregulated in the adult stage in response to heat stress. This study deepens our understanding of the mechanisms of TaPLC1-2B in regard to heat stress in wheat at the seedling and adult stages.

Omics for Elucidating Heat Stress Tolerance Mechanisms in Wheat: A Review Update

For the vast majority of people on earth, wheat is a primary staple food crop. It is one of the most vulnerable crops, the production of which significantly suffers from the harmful effects of climate change. As the predicted increase in global temperature is supposed to jeopardize production, wheat improvement towards heat stress-resilience has gained pivotal importance. The large and complex allohexaploid wheat genome represents a genetic puzzle, where deciphering any trait-genetics is always challenging. Fortunately, the advancement in the ‘omics’ approach has paved the way for solving these issues in a multidisciplinary convergent manner. The approach has significantly contributed towards the complex molecular mechanisms of the heat stress tolerance in wheat. In the recent past, salient attainments have been observed in exploring heat tolerance mechanisms in wheat addressed through omics technologies. All these approaches have identified some of the key regulators behind this complex trait, the conglomeration of which is definitely promising for achieving heat tolerant cultivars. Besides, the epigenetic regulation of this important trait as well as the significant achievements in developing heat tolerant lines through a transgenic approach has been enumerated. This summarized review of an issue of global importance should enlighten the understanding of the complex regulation of heat tolerance mechanism in wheat, which is a prerequisite for the development of stable heat tolerant wheat cultivars in near future. Here we discussed current research on the genetic and molecular variables that alter one's ability to tolerate heat, including the effects of epigenetic regulation. At the end, we concluded the review by discussing integrative methods for enhancing heat tolerance through the use of current germplasm, such as contemporary cultivars, landraces, and related species.

Conferring of Drought and Heat Stress Tolerance in Wheat (Triticum aestivum L.) Genotypes and Their Response to Selenium Nanoparticles Application

In this study, the role of selenium nanoparticles (SeNPs, 10 mg·L-1) has been investigated in modulating the negative effects of drought and heat stresses on eight bread wheat (Triticum aestivum L.) genotype seedlings. Those genotypes included Giza-168, Giza-171, Misr-1, Misr-3, Shandweel-1, Sids-1, Sids-12, and Sids-14. The study included six treatments as follows: regular irrigation with 100% Field Capacity (FC) at a temperature of 23 ± 3 °C (T1), drought stress with 60% FC (T2), heat stress of 38 °C for 5 h·day-1 (T3), foliar spray of 10 mg·L-1 of SeNPs only (T4), a combination of drought stress with foliar spray of 10 mg·L-1 of SeNPs (T5), and heat stress with foliar spray of 10 mg·L-1 of SeNPs (T6). The experiment continued for 31 days. Foliar application of SeNPs improved the plant growth, morpho-physiological and biochemical responses, and expression of stress-responsive genes in wheat (T. aestivum L.) seedlings. Overall, morpho-physiological traits such as plant height (PH), shoot fresh weight (SFW), shoot dry weight (SDW), root fresh weight (RFW), and root dry weight (RDW) of wheat genotypes grown under different conditions ranged from 25.37-51.51 cm, 3.29-5.15 g, 0.50-1.97 g, 0.72-4.21 g, and 0.11-1.23 g, respectively. From the morpho-physiological perspective, drought stress had a greater detrimental impact on wheat plants than heat stress, whereas heat stress significantly impacted the expression of stress-responsive genes. Stress responses to drought and heat varied between wheat genotypes, suggesting that different genotypes are more resilient to stress. Exogenous spraying of 10 mg·L-1 of SeNPs improved the photosynthetic pigments, photosynthetic rate, gas exchange, and transpiration rate of wheat plants and enhanced drought and heat tolerance by increasing the activity of antioxidant enzymes including catalase (CAT), ascorbate peroxidase (APX), and superoxide dismutase (SOD) and the expression level of stress-responsive genes. Our results showed that spraying wheat seedlings with 10 mg·L-1 of SeNPs enhanced SOD activity for all genotypes as compared to the control, with the Sids-12 genotype having the highest value (196.43 U·mg-1 FW·min-1) and the Giza-168 genotype having the lowest (152.30 U·mg-1 FW·min-1). The expression of PIP1, LEA-1, HSP70, and HSP90 stress-responsive genes was more significant in tolerant genotypes (Giza-171 and Giza-168) than in sensitive ones (Misr-1 and Misr-3) in response to drought and heat stresses. Under stress conditions, the shoot and root fresh weights, photosynthetic pigment content, stomatal conductance (SC), and transpiration rate (TR) were positively correlated with plant height (PH), while root and shoot dry weights, malondialdehyde (MDA), proline, hydrogen peroxide (H2O2), and APX were negatively correlated. Multivariate analysis and biplot results revealed that genotypes Giza-168, Giza-171, Sids-12, and Sids-14 performed well in both stress situations and were classified as stress-tolerant genotypes. These best genotypes may be employed in future breeding projects as tools to face climate change. This study concluded that various physio-biochemicals and gene expression attributes under drought and heat stress could be modulated by foliar application of SeNPs in wheat genotypes, potentially alleviating the adverse effects of drought and heat stress.

NDVI and grain fill duration are important to be considered in breeding for terminal heat stress tolerance in wheat

AbstractTerminal heat stress is a major constraint for taking a profitable crop of wheat by small and marginal farmers in the Indo‐Gangetic Plains of south Asia. Hence, breeders remain in constant search for heat‐tolerant genotypes. This study was done with the purpose to find out high‐yielding wheat genotypes that perform stably under terminal heat stress as well as to conclude an easy phenotyping trait for this objective. A cross (HUW 234 × HUW 468) was made using two popular cultivars of the eastern Gangetic Plains of India. HUW 234 carries terminal heat tolerance whereas, HUW 468 is high yielding but suffers from terminal heat stress when planted late. So obtained 167 recombinant inbred lines (RILs) were exposed to both timely sown (TS) and late sown (LS) conditions at three locations for two consecutive years 2016–17 and 2017–18 at Varanasi (Uttar Pradesh), Jabalpur (Madhya Pradesh) and Pusa, Samastipur (Bihar). Combined ANOVA revealed that normalized difference vegetation index (NDVI) at anthesis stage (NDVI_AH) and grain filling duration (GFD) was significant for genotype (G), environment (E) and genotype × environment interaction (GEI). Likewise, differences were significant for grain yield (GY) and 1000‐grain weight (TGW). AMMI analysis revealed similar results. However, NDVI_AH showed low variation under heat stressed late sown conditions. Furthermore, the which‐won‐where model and mean versus stability identified the best performing, above‐average yielding and stable lines across the environments. Correlation among measured traits revealed that NDVI_AH had a significant association with GY in most of the environments. Several lines that performed superior to better parent for GY also showed higher values for NDVI_AH and GFD. The study demonstrates that NDVI_AH and GFD appear to be important traits to be considered while breeding for terminal heat stress tolerance in wheat.

Molecular basis of heat stress tolerance in wheat

The rise in Earth’s temperature is one of the most alarming climatic issues in the field of agriculture and food production, in the present context. The increase in temperature leads to heat stress, major abiotic stress responsible for a huge decline in the production of crops. Wheat (Triticum aestivum), among many crops, also experiences a significant decline in yield and overall productivity due to extreme heat stress. But Wheat has also developed natural tolerance mechanisms to defend itself from heat damage. The selection of cultivars with a higher degree of tolerance mechanism protects against thermal stress, which minimizes the risk of poor productivity to a greater extent. In this review, we discuss the current works of literature concerning the heat stress tolerance mechanism in wheat plants and also highlight the strategic approaches that improve their heat stress tolerance at the molecular level. The success of these approaches depends on a better understanding of heat tolerance traits, their genomic composition, and molecular responses.

Histone acetyltransferase TaHAG1 interacts with TaNACL to promote heat stress tolerance in wheat.

Histone acetyltransferase TaHAG1 interacts with TaNACL to promote heat stress tolerance in wheat.

Heat Stress Tolerance 2 confers basal heat stress tolerance in allohexaploid wheat (Triticum aestivum L.).

Heat stress substantially reduces the yield potential of wheat (Triticum aestivum L.), one of the most widely cultivated staple crops, and greatly threatens global food security in the context of global warming. However, few studies have explored the heat stress tolerance (HST)-related genetic resources in wheat. Here, we identified and fine-mapped a wheat HST locus, TaHST2, which is indispensable for HST in both the vegetative and reproductive stages of the wheat life cycle. The studied pair of near isogenic lines (NILs) exhibited diverse morphologies under heat stress, based on which we mapped TaHST2 to a 485 kb interval on chromosome arm 4DS. Under heat stress, TaHST2 confers a superior conversion rate from soluble sugars to starch in wheat grains, resulting in faster grain filling and a higher yield potential. A further exploration of genetic resources indicated that TaHST2 underwent strong artificial selection during wheat domestication, suggesting it is an essential locus for basal HST in wheat. Our findings provide deeper insights into the genetic basis of wheat HST and might be useful for global efforts to breed heat-stress-tolerant cultivars.

An invasive weed-associated bacteria confers enhanced heat stress tolerance in wheat

Global temperatures are expected to increase due to climate change, and heat stress is one of the major limiting factors affecting future agriculture. To identify plant-associated microorganisms which can promote heat stress tolerance in wheat, we have screened several bacteria isolated from etiolated seedlings of the invasive noxious weed Parthenium hysterophorus. One isolate designated as Ph-04 was found to confer enhanced heat stress tolerance in wheat. The 16S rRNA gene sequence analysis showed that Ph-04 isolate shared highest sequence identity with Bacillus paramycoides species of the Bacillus cereus group. Ph-04 treated wheat seeds exhibited enhanced germination, longer coleoptile, radicle and seminal root length than control seedlings when grown in the dark at optimum and high temperatures. Similarly, under autotrophic conditions, Ph-04 treated plants also exhibited enhanced heat stress tolerance with a significant increase in membrane integrity and significantly reduced levels of H2O2 under heat stress compared to control plants. This observed heat stress tolerance is associated with constitutively higher basal levels of proline, and activity of antioxidant enzymes, catalase (CAT) and ascorbate peroxidase (APX) in Ph-04 treated plants grown under unstressed conditions with further increase under heat stress conditions compared to controls. Plant recovery after heat stress also showed that the Ph-04 treated plants exhibited significantly less damage in terms of survival percentage and exhibited better morphological and physiological characteristics compared to control plants. The study proves that invasive weeds can harbour potentially beneficial microorganisms, which can be transferred to non-native crop (host) plants to improve climate resilience characteristics.

RNA-Seq Analysis of Developing Grains of Wheat to Intrigue Into the Complex Molecular Mechanism of the Heat Stress Response.

Heat stress is one of the significant constraints affecting wheat production worldwide. To ensure food security for ever-increasing world population, improving wheat for heat stress tolerance is needed in the presently drifting climatic conditions. At the molecular level, heat stress tolerance in wheat is governed by a complex interplay of various heat stress-associated genes. We used a comparative transcriptome sequencing approach to study the effect of heat stress (5°C above ambient threshold temperature of 20°C) during grain filling stages in wheat genotype K7903 (Halna). At 7 DPA (days post-anthesis), heat stress treatment was given at four stages: 0, 24, 48, and 120 h. In total, 115,656 wheat genes were identified, including 309 differentially expressed genes (DEGs) involved in many critical processes, such as signal transduction, starch synthetic pathway, antioxidant pathway, and heat stress-responsive conserved and uncharacterized putative genes that play an essential role in maintaining the grain filling rate at the high temperature. A total of 98,412 Simple Sequences Repeats (SSR) were identified from de novo transcriptome assembly of wheat and validated. The miRNA target prediction from differential expressed genes was performed by psRNATarget server against 119 mature miRNA. Further, 107,107 variants including 80,936 Single nucleotide polymorphism (SNPs) and 26,171 insertion/deletion (Indels) were also identified in de novo transcriptome assembly of wheat and wheat genome Ensembl version 31. The present study enriches our understanding of known heat response mechanisms during the grain filling stage supported by discovery of novel transcripts, microsatellite markers, putative miRNA targets, and genetic variant. This enhances gene functions and regulators, paving the way for improved heat tolerance in wheat varieties, making them more suitable for production in the current climate change scenario.

Pollen viability as a potential trait for screening heat-tolerant wheat (Triticum aestivum L.).

High temperature during reproductive stage of winter crops causes sterility of pollen grains and reduced yield. It is essential to find the genotypes with higher pollen viability, as it is most sensitive to temperature extremes. A field study was conducted with wheat (Triticum aestivum L.) genotypes to understand the effect of high temperature on pollen viability and grain yield for 2years under timely (TS) and late sown (LS) conditions. A strong correlation was observed between higher pollen viability and higher grain yield under heat stress condition. Genotypes like K7903, HD2932, WH730 and RAJ3765 showed higher pollen viability, whereas DBW17, HUW468, RAJ4014 and UP2425 had lower pollen viability under LS condition. Further, the quantification of antioxidant enzymes activity mainly, Super oxide dismutase (SOD), Catalase (CAT), Peroxidase (POD) and Glutathione peroxidase (GPX) has showed significant variation among study genotypes. Thus, the identified high pollen viability genotypes can serve as a potential source for trait based breeding under heat stress in wheat. The present study is a first of its kind to assess more number of wheat genotypes for pollen viability and antioxidants activity under field condition. It also confirms that pollen viability can be used as a potential trait to screen genotypes for heat stress tolerance in wheat.

Exogenous application of silicon improves the performance of wheat under terminal heat stress by triggering physio-biochemical mechanisms

Due to climate change, temperature in late February and early March raised up which cause heat stress at reproductive stage (terminal growth phase of wheat crop) which has become the major causative factor towards low wheat production in arid and semiarid regions. Therefore; strategies need to be adopted for improving terminal heat stress tolerance in wheat. In this study, we assessed whether foliar application of silicon (Si) (2 and 4 mM) at terminal growth phase i.e. heading stage of wheat imposed to heat stress (37 ± 2 °C) under polythene tunnel could improve the performance of wheat. Results of the study revealed that heat stress significantly reduced the photosynthetic pigments (chlorophyll a, b and a + b and carotenoids) leading to a lower grain yield. However, a 4 mM Si application (foliar applied) at heading stage prominently increased the chlorophyll a, b and a + b and carotenoids of flag leaf by improving the activities of enzymatic antioxidants (catalase, peroxidase and superoxide dismutase) and osmoprotectants (soluble sugar protein and proline) under terminal heat stress. Improvements in the performance of wheat (chlorophyll contents, carotenoids, soluble sugar and proteins and proline and yield) with foliar application of Si were also observed under control conditions. Correlation analysis revealed strong association (r > 0.90) of chlorophyll contents and carotenoids with grain and biological yield. Negative correlation (−0.81 < r > −0.63) of physio-biochemical components (antioxidants, proline, soluble sugars and proteins) with yield revealed that under heat stress these components produced in more quantities to alleviate the effects of heat, and Si application also improved these physio biochemical components. In crux, foliar application of Si alleviates the losses in the performance of wheat caused by terminal heat stress by improving the antioxidant mechanism and production of osmoprotectants.

Physiological and molecular insights on wheat responses to heat stress.

Increasing temperature is a key component of global climate change, affecting crop growth and productivity worldwide. Wheat is a major cereal crop grown in various parts of the globe, which is affected severely by heat stress. The morphological parameters affected include germination, seedling establishment, source-sink activity, leaf area, shoot and root growth. The physiological parameters such as photosynthesis, respiration, leaf senescence, water and nutrient relation are also affected by heat. At the cellular level, heat stress leads to the generation of reactive oxygen species that disrupt the membrane system of thylakoid, chloroplast and plasma membrane. The deactivation of the photosystem, reduction in photosynthesis and inactivation of rubisco affect the production of photoassimilates and their allocation. This ultimately affects anthesis, grain filling, size, number and maturity of wheat grains, which hamper crop productivity. The interplay of various systems comprising antioxidants and hormones plays a crucial role in imparting heat stress tolerance in wheat. Thus, implementation of various omics technologies could foster in-depth insights on heat stress effects, eventually devising heat stress mitigation strategies by conventional and modern breeding to develop heat-tolerant wheat varieties. This review provides an integrative view of heat stress responses in wheat and also discusses approaches to develop heat-tolerant wheat varieties.

Late planting induced heat stress tolerance in wheat

Late planting induced heat stress tolerance in wheat

Understanding the Role of Gibberellic Acid and Paclobutrazol in Terminal Heat Stress Tolerance in Wheat.

Understanding the physiological mechanism of tolerance under stress conditions is an imperative aspect of the crop improvement programme. The role of plant hormones is well-established in abiotic stress tolerance. However, the information on the role of gibberellic acid (GA) in abiotic stress tolerance in late sown wheat is still not thoroughly explored. Thus, we aimed to investigate the role of endogenous GA3 level in stress tolerance in contrasting wheat cultivars, viz., temperature-tolerant (HD 2643 and DBW 14) and susceptible (HD 2189 and HD 2833) cultivars under timely and late sown conditions. We created the variation in endogenous GA3 level by exogenous spray of GA3 and its biosynthesis inhibitor paclobutrazol (PBZ). Tolerant genotypes had higher antioxidant enzyme activity, membrane stability, and photosynthesis rate, lower lipid peroxidase activity, and better growth and yield traits under late sown conditions attributed to H2O2 content. Application of PBZ escalated antioxidant enzymes activity and photosynthesis rate, and reduced the lipid peroxidation and ion leakage in stress, leading to improved thermotolerance. GA3 had a non-significant effect on antioxidant enzyme activity, lipid peroxidation, and membrane stability. However, GA3 application increased the test weight in HD 2643 and HD 2833 under timely and late sown conditions. GA3 upregulated GA biosynthesis and degradation pathway genes, and PBZ downregulated kaurene oxidase and GA2ox gene expression. GA3 also upregulated the expression of the cell expansins gene under both timely and late sown conditions. Exogenous GA3 did not increase thermotolerance but positively affected test weight and cell expansins gene expression. No direct relationship existed between endogenous GA3 content and stress tolerance traits, indicating that PBZ could have conferred thermotolerance through an alternative mechanism instead of inhibiting GA3biosynthesis.

Heterologous expression and characterization of novel manganese superoxide dismutase (Mn-SOD) – A potential biochemical marker for heat stress-tolerance in wheat (Triticum aestivum)

Heat stress causes oxidative bursts damaging the organelles and nascent proteins. Plants have inherited antioxidant defense system to neutralize the effect of reactive oxygen species. Superoxide dismutase provides first line of defense against the HS by regulating the accumulation of peroxide radicals inside the cells. Here, we report identification and cloning of putative manganese superoxide dismutase (Mn-SOD) gene of ~733 nt from wheat cv. HD2985 through de novo assembly. The gene was observed to localize on Chr 6D with a mitochondrial targeting peptide sequence and iron/manganese domain. We predicted 147 homologs of Mn-SOD in eukaryotes with diverse speciation nodes. A recombinant Mn-SOD protein of ~25.5 kDa was purified through heterologous expression system. Kinetics assay of recombinant protein showed optimum pH of 8.0, optimum temperature of 35 °C and Km and Vmax values of 1.51 μM and 9.45 U/mg proteins, respectively. Maximum expression and activity of Mn-SOD was observed in leaves from Raj3765, as compared to stem and spike during milky-ripe stage under differential HS. In gel activity assay showed the appearance of all the three isoforms of SOD in thermotolerant cv. under HS. Mn-SOD, being active at pivotal position, can be also used as potential biochemical marker in wheat breeding program.

Enhanced N-metabolites, ABA and IAA-conjugate in anthers instigate heat sensitivity in spring wheat.

Unraveling the metabolic and phytohormonal changes in anthers exposed to heat stress would help identify mechanisms regulating heat stress tolerance during the sensitive reproductive stage. Two spring wheat genotypes contrasting for heat tolerance were exposed to heat stress during heading in controlled environment chambers. Anthers were collected from main and primary spikes for metabolic and phytohormonal profiling. A significant reduction in seed set (38%), grain number (54%) and grain weight (52%) per plant was recorded in the sensitive (KSG1177) but not in the tolerant (KSG1214) genotype under heat stress compared to control. Anther metabolite accumulation did not vary quantitatively between main and primary spikes. Hierarchical clustering of the genotypes and treatments using metabolites and phytohormones revealed a distinct cluster for KSG1177 under heat stress from that of control and KSG1214. A significant increase in N-based amino acids, ABA, IAA-conjugate and a decrease in polyamines and organic acids were observed in wheat anthers exposed to heat stress. Unlike KSG1214, a significantly higher accumulation of amino acids, ABA and IAA-conjugate in anthers of the sensitive KSG1177 was recorded under heat stress. These findings provide the rationale and direction towards developing molecular markers for enhancing heat stress tolerance in wheat.

Novel Alleles for Combined Drought and Heat Stress Tolerance in Wheat.

Drought and heat waves commonly co-occur in many wheat-growing regions causing significant crop losses. The identification of stress associated quantitative trait loci, particularly those for yield, is problematic due to their association with plant phenology and the high genetic × environment interaction. Here we studied a panel of 315 diverse, spring type accessions of bread wheat (Triticum aestivum) in pots in a semi-controlled environment under combined drought and heat stress over 2 years. Importantly, we treated individual plants according to their flowering time. We found 134 out of the 145 identified loci for grain weight that were not associated with either plant phenology or plant height. The majority of loci uncovered here were novel, with favorable alleles widespread in Asian and African landraces providing opportunities for their incorporation into modern varieties through breeding. Using residual heterozygosity in lines from a nested association mapping population, we were able to rapidly develop near-isogenic lines for important target loci. One target locus on chromosome 6A contributed to higher grain weight, harvest index, thousand kernel weight, and grain number under drought and heat stress in field conditions consistent with allelic effects demonstrated in the genome-wide association study.

A review on conventional and molecular breeding approaches for exploring mechanisms underlying heat stress tolerance in wheat

A review on conventional and molecular breeding approaches for exploring mechanisms underlying heat stress tolerance in wheat

Genotype–Phenotype Relationships for High‐Temperature Tolerance: An Integrated Method for Minimizing Phenotyping Constraints in Wheat

Various attempts have been made to understand the traits and genes associated with heat stress tolerance in wheat (Triticum aestivum L.) in the field and under controlled conditions. Attempts made under controlled conditions have not been conclusive, mainly through a lack of sufficient precision in simulating the ambient temperature dynamics and microenvironments prevalent in the field. In addition, inconsistency in field phenotyping is a major concern. Hence, we attempted to develop a method for phenotyping wheat for heat stress tolerance through a novel temperature‐controlled phenotyping facility (TCPF), along with an inexpensive tool to ensure uniform crop establishment. The objective was to improve the precision of assessing plants' responses to elevated temperatures, particularly when these experiments are challenged by a large number of genotypes to be screened that show significant variations in their phenology. The study involved 75 genotypes from a recombinant inbred line population with differing responses to heat stress under three conditions: in the TCPF and in the field [regular field season and late sown (LS)] across two consecutive years. The results revealed that the yield components were different under LS and TCPF conditions. These differences reflected the plants' responses to morphophenological adaptations arising from the late planting time and were not really reflective of the heat stress response. However, greater precision in differentiating high‐temperature responses in the TCPF was evident from the repeatability in terms of growth, physiology, and productivity. This could be attributed to uniform crop establishment and improved capacity to maintain the desired temperature for phenotyping.

RuBisCo activase—a catalytic chaperone involved in modulating the RuBisCo activity and heat stress-tolerance in wheat

RuBisCo activase modulate the activity of RuBisCo and protect the nascent proteins from aggregation under heat stress (HS). Here, we have identified and cloned a putative RuBisCo activase (Rca) gene of 1402 bp from wheat cv. HD2985 using transcriptomic approach. Evolutionary search established the presence of 63 Orthologs and 2 Paralogs of the cloned Rca gene. Sequence analysis showed significant variations in the amino acid of Rca and RuBisCo (large and small subunit) in thermotolerant and thermosusceptible wheat cvs. Heterologous expression of Rca in E. coli showed the release of ~ 47 kDa purified protein. Expression analysis of Rca at transcript and protein level showed significant up-regulation in wheat cvs. Raj3765 (thermotolerant) and HD2329 (thermosusceptible) under HS. RuBisCo enzyme present in thermosusceptible cv. showed more sensitivity to HS, as compared to thermotolerant. Rca activity was observed higher in Raj3765 during pollination and milky-ripe stages under HS (38 °C, 1 h), as compared to HD2329. The binding of Rca with the RuBisCo under HS was observed more stable in Raj3765, as compared to HD2329. The purified Rca enzyme was observed more effective in the renaturation of RuBisCo (inactive) under HS in Raj3765 than in HD2329. A positive correlation was established between the Rca enzyme activity and radical scavenging potential in the leaves of both the wheat cvs. under HS. There is a need to characterize the enzyme kinetics and functional diversity of Rca in order to exploit it in a better way to augment the carbon assimilatory processes in wheat under differential HS.