Crosstalk of heat shock proteins and antioxidants with peroxisome biogenesis supports wheat thermotolerance

Rising temperatures globally impose coupled proteotoxic and oxidative stresses that limit spring wheat (Triticum aestivum) productivity, yet how protein quality control, redox homeostasis, and peroxisome dynamics are coordinately regulated during thermotolerance remains unclear. Here, we investigated the integrated roles of heat shock proteins (HSPs), antioxidant defenses, and peroxisome biogenesis in two contrasting wheat genotypes differing in heat stress tolerance at anthesis: Misr2 (tolerant) and Line4 (susceptible). Heat responses were characterized by osmoprotectant accumulation (total soluble sugars, proline), oxidative stress markers (malondialdehyde, hydrogen peroxide), antioxidant enzyme activities (CAT, SOD, POX), peroxisome abundance, and expression of stress-responsive genes. Integrated phenotype-gene association analyses distinguished thermotolerant and susceptible responses in Misr2 and Line4 by resolving coordinated regulatory modules. Expression profiles of eight candidate genes (TaHSP70, TaHSP90, TaSOD, TaCAT1, TaPEX11.3, TaPEX11.4, TaFIS1A, and TaDRP5B), analyzed in conjunction with phenotypic traits, revealed modular gene networks linking antioxidant defenses, HSP-mediated proteostasis, and peroxisome proliferation. TaHSP70, TaPEX11.4, and TaCAT1 functioned as regulatory hubs, TaDRP5B and TaSOD as phenotypic switch nodes, and TaPEX11.3, TaFIS1A, and TaHSP90 as context-dependent responders. Together, these findings uncover modular crosstalk among heat-stress pathways that underpin wheat thermotolerance, providing molecular targets for breeding heat-resilient cultivars under climate change.