Physiological and proteomics approaches for deciphering heat-stress tolerance in bread wheat (Triticum aestivum L.).

Heat-stress has detrimental effects on global bread wheat (Triticum aestivum L.) productivity. The aim of our study was to identify proteomic biomarkers for heat tolerance in wheat. We compared physiology, yield, and protein abundance changes of wheat genotypes with contrasting heat tolerance [two tolerant (RAJ3765 and HD2932) and two susceptible (HD2329 and HD2733)] under short-term and long-term heat-stress (32°C) at ear peep. This experiment revealed that heat tolerant genotypes-maintained grain yield under both short- and long-term heat exposure by maintaining photosynthesis, membrane stability, chlorophyll content, pollen viability, and redox homeostasis. We identified 31 and 60 changes in protein abundance in flag-leaves and spike tissues respectively. These revealed key pathways responsive to heat, including photosynthesis, RNA processing, heat-shock proteins, redox homeostasis, carbohydrate metabolism, protein breakdown, translation and translocation, stress-induced accumulation, and chromatin organization in flag-leaves. In contrast carbohydrate, lipid and secondary metabolism, cell wall organization, redox homeostasis, chromatin organization, membrane transport, methylation, protein folding, breakdown and translocation, RNA processing, lipid transfer, cell morphogenesis, heat-shock proteins and reproduction were prominent in spikes. Co-expression analysis revealed networks of proteins co-related to agronomic traits. These proteins can be used as biomarkers for heat tolerance in future breeding programs.