ABSTRACT Heat stress increasingly threatens global wheat production as extreme temperature events become more frequent under climate change. To better understand the molecular basis of thermotolerance, we evaluated the heat responses of 30 elite wheat accessions and identified substantial natural variation in seedling survival (26.7%), plant height (26.0%–68.8%), and shoot fresh weight (5.7%–86.2%). We subsequently conducted time‐resolved transcriptome profiling of two contrasting genotypes, the heat‐resistant Huaimai211 and the heat‐susceptible Chuke316 , across five heat‐stress durations. RNA‐seq analysis revealed 8517 and 4155 genes that were consistently responsive to heat stress in the HR and HS genotypes, respectively, with 3028 core genes shared by both genotypes. These core genes were further enriched in pathways related to Hsp90 binding, protein folding, the unfolded protein response, and glutathione metabolism. Conversely, genes associated with photosynthesis, chlorophyll‐binding proteins, and Calvin‐cycle enzymes were persistently downregulated across all time points, indicating sustained repression of photosynthetic processes during prolonged heat exposure. Genotype‐specific analyses revealed that HR uniquely activated metabolic and protein‐folding pathways related to amino‐acid biosynthesis, fructose‐bisphosphate aldolase activity, and peptidyl‐prolyl isomerase function. Co‐expression network analysis identified several heat‐associated modules, among which the firebrick3 module showed the strongest association with thermotolerance and highlighted TaRbcS‐2B.3 as a hub gene linking photosynthetic adjustment to stress adaptation. Together, these results reveal a coordinated heat‐response framework involving persistent photosynthetic suppression, reinforcement of proteostasis, and genotype‐specific metabolic plasticity. The identified pathways and candidate genes provide valuable targets for marker‐assisted selection, gene editing, and genomic prediction efforts aimed at improving wheat thermotolerance, thereby supporting yield stability under increasingly frequent heat events.
Jiang et al. (Sun,) studied this question.