Heat Tolerance In Rice Research Articles

Exploring the impacts of climate change and identifying potential adaptation strategies for sustainable rice production in Thailand's Lower Chao Phraya Basin through crop simulation modeling.

The lower Chao Phraya River Basin (CPRB) in Thailand, a major rice-producing area, is grappling with increased water scarcity alongside more frequent floods and droughts, necessitating effective adaptation strategies to sustain agricultural productivity. This study assesses the impacts of climate change on rice yield and irrigation water use, using the DSSAT-CERES-Rice model. Based on these findings, potential genotype- and management-based adaptation strategies were recommended. The model was calibrated and evaluated using the data from field experiments conducted at the Asian Institute of Technology, Thailand during 2017-2018 and 2021-2022. The grain yield and irrigation water use between baseline (2010-2022) and future climate periods (early-century: 2023-2040, mid-century: 2041-2070, and late-century: 2071-2100) were compared. Future climate projections were based on five Global Climate Models (GCMs) from the NEX-GDDP-CMIP6 project under three scenarios (SSP126, SSP245, and SSP585). The model calibration and evaluation demonstrated very good performance statistics, with a d-index of 0.85 during both calibration and evaluation. The model simulations indicated that the maximum and minimum temperatures in the lower CPRB are projected to increase by ~ 2 °C and ~ 4 °C in the late century under SSP245 and SSP585, respectively. Consequently, rice yields are projected to decline by up to 33%, and irrigation water usage to increase by 53% under SSP585 by the late century. Based on the findings, the following major genotype- and management-based adaptation strategies are recommended: (1) Developing heat-tolerant rice cultivars to mitigate yield losses under future climate scenarios, (2) Developing rice cultivars with extended grain-filling duration to enhance both irrigation water use and yield, (3) Shifting the planting date 1-2 weeks earlier (from baseline planting date of 20 July), and shifting fertilizer application date 1-2 weeks earlier (from baseline fertilizer application date of 20 September) for the panicle initiation stage to improve yield, and (4) Optimizing irrigation thresholds (remaining soil water at which to irrigate) to reduce irrigation water use without compromising yield. Overall, the findings highlight the importance of genotype improvement and adaptive management practices in mitigating the adverse effects of climate change on rice production in the lower CPRB.

Histone demethylase JMJ713 interaction with JMJ708 modulating H3K36me2, enhances rice heat tolerance through promoting hydrogen peroxide scavenging

The Earth is currently undergoing rapid warming cause of the accumulation in greenhouse gas emissions into the atmosphere and the consequent rise in global temperatures. High temperatures can bring the effects on rice development and growth (Oryza sativa) and thereby decrease rice yield. In this study, we have identified that both JMJ713 and JMJ708 possess distinct histone demethylase activities. Specifically, JMJ713 modulates the levels of H3K36me2 while JMJ708 alters H3K9me3. Additionally, we have observed an interaction between JMJ713 and JMJ708, which collectively modify the level of H3K36me2. Furthermore, our findings demonstrate that JMJ713 plays an essential role to heat stress responses in rice. The overexpression of JMJ713 enhances heat tolerance in rice, whereas JMJ713 RNA interference rice lines exhibit increased sensitivity to heat. Further investigations revealed that overexpression of JMJ713 activated catalase (CAT) and peroxidase (POD) activities by mitigating excessive accumulation of reactive oxygen species (ROS) caused by heat stress. Interestingly, the setting rates of JMJ713 RNA interference lines decreased in comparing to wild-type, indicating that JMJ713 might play a crucial role in the rice seed development stage as well. Collectively, Overall, this study not only highlights JMJ713 is involved in heat stress responses but also provides insights into the conserved Fe(Ⅱ) and α-ketoglutarate (KG) binding residues are crucial for the demethylase activity of JMJ713, as well as JMJ713 interacts with JMJ708 to jointly regulate the levels of H3K36me2.

Marker assisted selection and genome recovery for heat tolerance in segregants of rice (Oryza sativa L.)

Abstract In the present global warming scenario, it is urgent to impart heat tolerance into the popular high yielding rice (Oryza sativa L.) varieties to reduce yield loss to a great extent. Uma (a prevalent red-grained rice variety in Kerala) was crossed with Nagina 22 (N22), the popular donor for heat tolerance. From the seven promising heat-tolerant F3 plants previously identified through marker assisted selection and field screening, F4 lines (58 nos.) were raised and characterised morphologically. Heat tolerance was scored under natural heat stress during hot summer months in field conditions. Among the evaluated F4 progenies, 26 promising plants registered >75% spikelet fertility. Double panicles were observed in some of the tillers of fourteen F4 plants. During the selection with reported polymorphic markers between parents, all the 26 F4 plants produced the corresponding amplicon for RM5749 (linked marker for heat tolerance in the parental cross Uma x N22) and also for RM9, RM201, RM208, RM225, RM242, RM495, RM3586, RM6100, RM6836, and RM26212, corresponding to the heat tolerant parent N22. Genomic analysis revealed 64% recovery of the Uma genome in seven F4 plants, with maximum genomic regions of Uma on the chromosomes 3 and 5. These promising F4 plants could be forwarded to generate stable and high yielding heat tolerant rice varieties. The identified markers could be used for linkage analysis and QTL mapping in future. Keywords: Heat stress; Rice; spikelet fertility; SSR; QTL

OsRHS Negatively Regulates Rice Heat Tolerance at the Flowering Stage by Interacting With the HSP Protein cHSP70-4.

Heat stress at the flowering stage significantly impacts rice grain yield, yet the number of identified genes associated with rice heat tolerance at this crucial stage remains limited. This study focuses on elucidating the function of the heat-induced gene reduced heat stress tolerance 1 (OsRHS). Overexpression of OsRHS leads to reduced heat tolerance, while RNAi silencing or knockout of OsRHS enhances heat tolerance without compromising yield, as assessed by the seed setting rate. OsRHS is localized in the cytoplasm and mainly expressed in the glume and anther of spikelet. Moreover, OsRHS was found to interact with the HSP protein cHSP70-4, and the knockout of cHSP70-4 resulted in increased heat tolerance. Complementation assays revealed that the knockout of cHSP70-4 could restore the compromised heat tolerance in OsRHS overexpression plants. Additional investigation reveals that elevated temperatures can amplify the bond between OsRHS and cHSP70-4 within rice. Furthermore, our findings indicate that under heat stress conditions during the flowering stage, OsRHS plays a negative regulatory role in the expression of many stress-related genes. These findings unveil the crucial involvement of OsRHS and cHSP70-4 in modulating heat tolerance in rice and identify novel target genes for enhancing heat resilience during the flowering phase in rice.

Effects of high temperature on grain quality and enzyme activity in heat-sensitive versus heat-tolerant rice cultivars.

High-temperature (HT) stress significantly affects the quality of rice (Oryza sativa L.), although the underlying the mechanism remains unknown. Therefore, in the present study, we assessed protein components, amino acids, mineral element levels, starch biosynthesis enzyme activity and gene expression of two heat-sensitive and two heat-tolerant genotypes under HT treatment during early (from 1 to 10 days, T1) and mid-filling (from 11 to 20 days, T2) after anthesis. Except for one cultivar, most rice varieties exhibited increased levels of amylose, chalky degree and protein content, along with elevated cracked grains and pasting temperatures and, consequently, suppressed amino acid levels under HT stress. HT treatment also increased protein components, macro- (Mg, K, P and S) and microelements (Cu, Zn, and Mo) in the rice flour. Both HT treatments reduced the activity of ADP-glucose pyrophosphate, ground-bound starch synthase, as well as the relative ratio of amylose to total starch, at the same time increasing starch branch enzyme activity. The expression levels of OsAGPL2, OsSSS1 and OsSBE1 in all varieties exhibited the same trends as enzyme activity under HT treatment. High temperatures negatively affected rice quality during grain filling, which is related to heat tolerance and grain shape. Altered enzymatic activity is crucial to compensate for the lowered enzyme quality under heat stress. © 2024 Society of Chemical Industry.

Effect of Heat Stress during Reproductive Stage on Plant Growth, Total Biomass Production and their Correlation with Grain Yield in Rice

Rice (Oryza sativa L.) is highly sensitive to high temperature during its reproductive stages. This study aims to elucidate the effects of heat stress during reproductive stage on plant growth, total dry matter accumulation, and their correlation with grain yield in diverse rice genotypes. A field experiment in split plot design was conducted at G.B.P.U.A.& T., Pantnagar during rainy season 2022-23, where high temperature stress was imposed on 15 rice genotypes during reproductive stage (after panicle initiation till maturity) using a polytunnel. The results showed that heat stress lead to reduction in dry matter accumulation and harvest index in 10 genotypes, although with different magnitude. The genotypes were screened into tolerant and susceptible based on yield reduction by comparing with the genotype N-22, which was used as a check for heat stress. It was observed that the genotypes, IET 29415, MTU-1282, MTU-1121, NLR-40042 and US-314 maintaining higher biomass and HI under heat stress conditions were able to maintain grain yield. The identified genotypes with better performance under heat stress conditions offer valuable genetic resources for breeding programs aimed at improving heat tolerance in rice.

Screening of heat stress-tolerant weedy rice and SNP identification of heat-tolerance-related genes

Rice, a staple crop that feeds more than one-third of the world’s population, encounters a wide range of biotic and abiotic stresses due to climate change. Rising temperature is one of the significant abiotic stresses affecting rice productivity worldwide. The development of heat-tolerant rice cultivars is critical in this regard. Weedy rice could potentially serve as a natural resource for genes conferring agronomically important traits beneficial to cultivated rice. However, heat tolerance in both cultivated and weedy rice is still understudied. This study screened a set of 180 weedy rice accessions for heat stress tolerance and further characterised them using genome-wide single-nucleotide polymorphisms (SNPs) analysis. Five heat-tolerant (HT) accessions (MU244, MU235, MU249, MU260 and MU237), along with five heat-susceptible (HS) accessions (MU100, MU114, MU264, MU251 and MU005), were subjected to relative electrical conductivity (REC) test and reactive oxidative species assay (ROS). These tests verified that the five HT accessions performed better under heat stress than their HS counterparts. In addition, whole-genome sequences of three HT (MU235, MU237 and MU066) and four HS (MU100, MU114, MU022 and MU005) accessions were selected for the genome-wide SNPs comparison, revealing substantial amino acid variation in the heat-tolerance-related genes between the HT and HS rice groups. The proposed genes and genome-wide SNP markers may help rice breeders better understand how different rice cultivars respond to heat stress.

Stress-induced nuclear translocation of ONAC023 improves drought and heat tolerance through multiple processes in rice

Drought and heat are major abiotic stresses frequently coinciding to threaten rice production. Despite hundreds of stress-related genes being identified, only a few have been confirmed to confer resistance to multiple stresses in crops. Here we report ONAC023, a hub stress regulator that integrates the regulations of both drought and heat tolerance in rice. ONAC023 positively regulates drought and heat tolerance at both seedling and reproductive stages. Notably, the functioning of ONAC023 is obliterated without stress treatment and can be triggered by drought and heat stresses at two layers. The expression of ONAC023 is induced in response to stress stimuli. We show that overexpressed ONAC23 is translocated to the nucleus under stress and evidence from protoplasts suggests that the dephosphorylation of the remorin protein OSREM1.5 can promote this translocation. Under drought or heat stress, the nuclear ONAC023 can target and promote the expression of diverse genes, such as OsPIP2;7, PGL3, OsFKBP20-1b, and OsSF3B1, which are involved in various processes including water transport, reactive oxygen species homeostasis, and alternative splicing. These results manifest that ONAC023 is fine-tuned to positively regulate drought and heat tolerance through the integration of multiple stress-responsive processes. Our findings provide not only an underlying connection between drought and heat responses, but also a promising candidate for engineering multi-stress-resilient rice.

Quantifying the Individual and Combined Effects of Short-Term Heat Stress at Booting and Flowering Stages on Nonstructural Carbohydrates Remobilization in Rice.

Rice production is threatened by climate change, particularly heat stress (HS). Nonstructural carbohydrates (NSCs) remobilization is a key physiological mechanism that allows rice plants to cope with HS. To investigate the impact of short-term HS on the remobilization of nonstructural carbohydrates (NSCs) in rice, two cultivars (Huaidao-5 and Wuyunjing-24) were subjected to varying temperature regimes: 32/22/27 °C as the control treatment, alongside 40/30/35 °C and 44/34/39 °C, for durations of 2 and 4 days during the booting, flowering, and combined stages (booting + flowering) within phytotrons across the years 2016 and 2017. The findings revealed that the stem's NSC concentration increased, while the panicle's NSCs concentration, the efficiency of NSCs translocation from the stem, and the stem NSC contribution to grain yield exhibited a consistent decline. Additionally, sugar and starch concentrations increased in leaves and stems during late grain filling and maturity stages, while in panicles, the starch concentration decreased and sugar concentration increased. The heat-tolerant cultivar, Wuyunjing-24, exhibited higher panicle NSC accumulation under HS than the heat-sensitive cultivar, Huaidao-5, which had more stem NSC accumulation. The flowering stage was the most vulnerable to HS, followed by the combined and booting stages. Heat degree days (HDDs) were utilized to quantify the effects of HS on NSC accumulation and translocation, revealing that the flowering stage was the most affected. These findings suggest that severe HS makes the stem the primary carbohydrate storage sink, and alleviation under combined HS aids in evaluating NSC accumulation, benefiting breeders in developing heat-tolerant rice varieties.

Micrometeorological monitoring reveals that canopy temperature is a reliable trait for the screening of heat tolerance in rice.

Micrometeorological monitoring is not just an effective method of determining the impact of heat stress on rice, but also a reliable way of understanding how to screen for heat tolerance in rice. The aim of this study was to use micrometeorological monitoring to determine varietal differences in rice plants grown under two weather scenarios-Long-term Heat Scenario (LHS) and Normal Weather Scenario (NWS)- so as to establish reliable methods for heat tolerance screening. Experiments were conducted with two heat susceptible varieties-Mianhui 101 and IR64-and two heat tolerant varieties, Quanliangyou 681 and SDWG005. We used staggered sowing method to ensure that all varieties flower at the same time. Our results showed that heat tolerant varieties maintained lower canopy temperature compared to heat susceptible varieties, not just during the crucial flowering period of 10 am to 12 pm, but throughout the entire day and night. The higher stomatal conductance rate observed in heat tolerant varieties possibly decreased their canopy temperatures through the process of evaporative cooling during transpiration. Conversely, we found that panicle temperature cannot be used to screen for heat tolerance at night, as we observed no significant difference in the panicle temperature of heat tolerant and heat susceptible varieties at night. However, we also reported that higher panicle temperature in heat susceptible varieties decreased spikelet fertility rate, while low panicle temperature in heat tolerant varieties increased spikelet fertility rate. In conclusion, the results of this study showed that canopy temperature is probably the most reliable trait to screen for heat tolerance in rice.

Novel QTLs from Wild Rice Oryza longistaminata Confer Strong Tolerance to High Temperature at Seedling Stage

Global warming poses a threat to rice production. Breeding heat-tolerant rice is an effective and economical approach to addressing this challenge. African rice is a valuable genetic resource for developing heat-tolerant crops due to its intricate mechanism for adapting to high temperatures. Oryza longistaminata, a wild rice species widely distributed in Africa, may harbor an even richer gene pool for heat tolerance, which remains untapped. In this study, we identified three heat-tolerant QTLs from O. longistaminata at the seedling stage. Among these, qTT4 and qTT5 are novel heat-tolerant loci identified in O. longistaminata. Our findings demonstrated that the O. longistaminata alleles for these two QTLs can enhance the heat tolerance of rice seedlings. Remarkably, qTT5 was mapped to a region spanning approximately 287.2 kb, containing 46 expressing genes. Through the analysis of Gene Ontology and expression differences under heat induction, we identified four candidate genes. Our results lay the foundation for the discovery of heat-tolerant genes underlying O. longistaminata and the development of new genetic resources for heat tolerant rice breeding.

Brassinosteroid modulates ethylene synthesis and antioxidant metabolism to protect rice (Oryza sativa) against heat stress-induced inhibition of source‒sink capacity and photosynthetic and growth attributes

This study presents an exploration of the efficacy of brassinosteroids (BRs) and ethylene in mediating heat stress tolerance in rice (Oryza sativa). Heat is one of the major abiotic factors that prominently deteriorates rice production by influencing photosynthetic efficiency, source‒sink capacity, and growth traits. The application of BR (0.5 mM) and ethylene (200 μl l−1) either individually and/or in combination was found to alleviate heat stress-induced toxicity by significantly improving photosynthesis, source‒sink capacity and defense systems; additionally, it reduced the levels of oxidative stress markers and ethylene formation. The study revealed the positive influence of BR in promoting plant growth responses under heat stress through its interplay with ethylene biosynthesis and enhanced plant defense systems. Interestingly, treatment with the ethylene biosynthesis inhibitor aminoethoxyvinylglycine (AVG) substantiated that BR application to heat-stressed rice plants enhanced ethylene-dependent pathways to counteract the underlying adversities. Thus, BR action was found to be mediated by ethylene to promote heat tolerance in rice. The present study sheds light on the potential tolerance mechanisms which can ensure rice sustainability under heat stress conditions.

Booting heat stress alters leaf photosynthesis, growth rate, phenology and yield in rice

BackgroundThe phenomenon of global warming results in a significant rise in temperature which adversely affects the growth, physiology, and yield of rice. In order to gain insight into the impacts of booting heat stress (at 42 °C, 3 h for 7 days), we investigated its effect in three rice genotypes, namely, N22, KDML105 and IR64. ResultsBooting heat stress caused an extended phenology and a lower photosynthesis and plant growth rate but an increase in chalkiness. Although, the prolonged phenology from dough to physiological maturity resulted in a longer duration of grain filling, the adverse effects of this were a significantly lower yield component, yield and harvest index across all varieties of rice. Among cultivars, N22 demonstrated an adapted ability to maintain leaf gas exchange and compensated for the vegetative part by an increase in tiller numbers resulting in a less affected growth rate. It caused extended grain filling by prolonging the phenology. Consequence, N22 had the lowest reduction in number of seed panicle−1, number of filled seeds hill−1, yield, harvest index, and percentage chalkiness. KDML105 was adapted to booting heat stress by maintaining leaf gas exchange, increasing specific leaf area and prolonging phenology. The longest extended phenology and high photosynthesis during dough grain were associated with moderate yield reduction and chalkiness. Nonetheless, IR64 demonstrated significant reductions in photosynthesis, growth rate, and yield but the highest percentage of grain chalkiness. ConclusionTherefore, the response of N22, KDML105 and IR64 to booting heat stress could be indicated as being heat tolerant, moderately heat sensitive, and heat sensitive, respectively. This approach can be applied to crop modeling and rice heat tolerance in breeding programs.

Long and Short-Run Effects of Climate Change on Boro Rice Productivity: An Empirical Evidence from Bangladesh

This study endeavors to examine the effect of climate change on Boro rice productivity in Bangladesh. Unit root, Co-integration and Vector Error Correction Model estimation technique are applied to measure the climate-crop yield interrelation on the basis of country level time series data for the period 1972-2019. Average maximum and minimum temperature, rainfall and humidity are used to attribute variables for climate change. The result of vector error correction model denotes that both in the long-run and short-run, average maximum temperature, average total rainfall and humidity negatively effect on Boro rice productivity in Bangladesh respectively. On the other hand, Average minimum temperature is positively effect on Boro rice productivity in the short-run. Fertilizer and irrigation have positive effect on Boro rice productivity in the short-run respectively. Conversely, labor has robust negative effect on Boro rice productivity in the short-run in Bangladesh agriculture. Policy maker should develop policies to mitigate temperature and introduce heat tolerant rice varieties and adaptation measure to sustain the Boro rice productivity in Bangladesh.

Chlorophyll fluorescence-based high-throughput phenotyping facilitates the genetic dissection of photosynthetic heat tolerance in African (Oryza glaberrima) and Asian (Oryza sativa) rice.

Rising temperatures and extreme heat events threaten rice production. Half of the global population relies on rice for basic nutrition, and therefore developing heat-tolerant rice is essential. During vegetative development, reduced photosynthetic rates can limit growth and the capacity to store soluble carbohydrates. The photosystem II (PSII) complex is a particularly heat-labile component of photosynthesis. We have developed a high-throughput chlorophyll fluorescence-based screen for photosynthetic heat tolerance capable of screening hundreds of plants daily. Through measuring the response of maximum PSII efficiency to increasing temperature, this platform generates data for modelling the PSII-temperature relationship in large populations in a small amount of time. Coefficients from these models (photosynthetic heat tolerance traits) demonstrated high heritabilities across African (Oryza glaberrima) and Asian (Oryza sativa, Bengal Assam Aus Panel) rice diversity sets, highlighting valuable genetic variation accessible for breeding. Genome-wide association studies were performed across both species for these traits, representing the first documented attempt to characterize the genetic basis of photosynthetic heat tolerance in any species to date. A total of 133 candidate genes were highlighted. These were significantly enriched with genes whose predicted roles suggested influence on PSII activity and the response to stress. We discuss the most promising candidates for improving photosynthetic heat tolerance in rice.

Time-Series Transcriptomic Analysis of Contrasting Rice Materials under Heat Stress Reveals a Faster Response in the Tolerant Cultivar.

Short-term heat stress can affect the growth of rice (Oryza sativa L.) seedlings, subsequently decreasing yields. Determining the dynamic response of rice seedlings to short-term heat stress is highly important for accelerating research on rice heat tolerance. Here, we observed the seedling characteristics of two contrasting cultivars (T11: heat-tolerant and T15: heat-sensitive) after different durations of 42 °C heat stress. The dynamic transcriptomic changes of the two cultivars were monitored after 0 min, 10 min, 30 min, 1 h, 4 h, and 10 h of stress. The results indicate that several pathways were rapidly responding to heat stress, such as protein processing in the endoplasmic reticulum, glycerophospholipid metabolism, and plant hormone signal transduction. Functional annotation and cluster analysis of differentially expressed genes at different stress times indicate that the tolerant cultivar responded more rapidly and intensively to heat stress compared to the sensitive cultivar. The MAPK signaling pathway was found to be the specific early-response pathway of the tolerant cultivar. Moreover, by combining data from a GWAS and RNA-seq analysis, we identified 27 candidate genes. The reliability of the transcriptome data was verified using RT-qPCR on 10 candidate genes and 20 genes with different expression patterns. This study provides valuable information for short-term thermotolerance response mechanisms active at the rice seedling stage and lays a foundation for breeding thermotolerant varieties via molecular breeding.

Effect of Global Warming on Agricultural Productivity

Purpose: The aim of the study is to examine the effect of global warming on Agricultural productivity
 Methodology: This study adopted a desktop methodology. This study used secondary data from which include review of existing literature from already published studies and reports that was easily accessed through online journals and libraries.
 Findings: The study revealed that farmers are experiencing changes in temperature and precipitation patterns including more frequent and intense droughts and floods. These changes are leading to lower crop yields and incomes. The study also found that farmers were aware of the impact of climate change on agriculture and had adopted several adaptation strategies, including changing planting dates, selecting heat-tolerant rice varieties, and applying organic fertilizers
 Unique Contribution to Theory, Practice and Policy: The study was anchored on Resilience Theory which originated from the work of C.S. Holling and Social-Constructivist Theory which originated from the works of Lev Vygotsky. The study recommends that farmers should adopt climate-smart agricultural practices, such as conservation agriculture and improved water management, to increase their resilience to climate change. The study also recommends that farmers should be given support to enable them to adapt to the changing climatic conditions including access to finance, education and training

Influence of Climate Factors on Aman Rice Yield in Bangladesh: Co-Integration and Vector Error Correction Model Approach

Climate factors’ consequence on human performance has occurred as a worldwide apprehension in the earlier 30 years. This study explores climate factors’ influence on Aman rice production in Bangladesh. Co-integration and Vector Error Correction Model approximation procedure is applied to measure the climate-crop harvest interrelation on the basis of country-level time series data for the time 1972-2019. Changing in mean maximum and minimum temperature, annual men rainfall, and average humidity are used as characteristic variables for climate factors. The result of the vector error correction model denotes that both in the long-run and short-run, average maximum temperature and average total rainfall inversely affect Aman rice yield in Bangladesh respectively. Average minimum temperature and average humidity positively affect Aman rice production in the short run respectively. Fertilizers and irrigation have a positive influence on Aman rice yield in the short-run correspondingly. Conversely, labor has a robust negative consequence on Aman rice yield in the short-run in Bangladesh agriculture. Policymakers would develop policies to control temperature and introduce heat-tolerant rice varieties and adaptation measures to sustain Aman rice production in Bangladesh.

ENHANCED DISEASE SUSCEPTIBILITY 1 promotes hydrogen peroxide scavenging to enhance rice thermotolerance.

Heat stress is a major factor limiting the production and geographic distribution of rice (Oryza sativa), and breeding rice varieties with tolerance to heat stress is of immense importance. Although extensive studies have revealed that reactive oxygen species (ROS) play a critical role in rice acclimation to heat stress, the molecular basis of rice controlling ROS homeostasis remains largely unclear. In this study, we discovered a novel heat-stress-responsive strategy that orchestrates ROS homeostasis centering on an immune activator, rice ENHANCED DISEASE SUSCEPTIBILITY 1 (OsEDS1). OsEDS1, which confers heat stress tolerance, promotes hydrogen peroxide (H2O2) scavenging by stimulating catalase activity through the OsEDS1-catalase association. The loss-of-function mutation in OsEDS1 causes increased sensitivity to heat stress, whereas the overexpression of OsEDS1 enhances thermotolerance. Furthermore, overexpression lines greatly improved rice tolerance to heat stress during the reproductive stage, which was associated with substantially increased seed setting, grain weight, and plant yield. Rice CATALASE C (OsCATC), whose activity is promoted by OsEDS1, degrades H2O2 to activate rice heat stress tolerance. Our findings greatly expand our understanding of heat stress responses in rice. We reveal a molecular framework that promotes heat tolerance through ROS homeostasis regulation, suggesting a theoretical basis and providing genetic resources for breeding heat-tolerant rice varieties.

Genetic Research Progress: Heat Tolerance in Rice.

Heat stress (HS) caused by high-temperature weather seriously threatens international food security. Indeed, as an important food crop in the world, the yield and quality of rice are frequently affected by HS. Therefore, clarifying the molecular mechanism of heat tolerance and cultivating heat-tolerant rice varieties is urgent. Here, we summarized the identified quantitative trait loci (Quantitative Trait Loci, QTL) and cloned rice heat tolerance genes in recent years. We described the plasma membrane (PM) response mechanisms, protein homeostasis, reactive oxygen species (ROS) accumulation, and photosynthesis under HS in rice. We also explained some regulatory mechanisms related to heat tolerance genes. Taken together, we put forward ways to improve heat tolerance in rice, thereby providing new ideas and insights for future research.