Physiological and transcriptional analyses of induced post-anthesis thermo-tolerance by heat-shock pretreatment on germinating seeds of winter wheat

• Heat shock during germination induced post-anthesis thermo-tolerance in wheat.
• Improved photosynthesis and antioxidation contributed to acquired thermo-tolerance.
• Modified gene expressions conferred enhanced photosynthesis and antioxidation.
• Heat shock proteins played important roles in the acquired thermo-tolerance.

Heat stress occurring during grain filling is a worldwide environmental constraint limiting wheat production. To evaluate the alleviation effects of heat-shock pretreatment during germination on post-anthesis heat stress, germinating seeds were firstly heat-shocked at 40 °C for four hours. The plants were later given a five-day high temperature stress from ten days after anthesis. The post-anthesis heat stress resulted in significant grain yield reduction. However, the heat-shock pretreatment caused less yield loss. Physiological analyses revealed that capacities of leaf photosynthesis and antioxidation were improved to benefit the less yield loss in the pretreated plants. This was consistent with the differentially regulated expressions of the involving genes as revealed by the transcriptomic analysis. In addition, the transcriptome profiling indicated that the stress signaling processes were triggered, and expressions of stress related genes such as heat-shock proteins and osmotins were up-regulated in the pretreated plants. Thus, the up-regulated physiological processes of photosynthesis, antioxidation and HSPs accumulation because of the modified expressions of the related genes could contribute to the enhanced thermo-tolerance induced by heat-shock pretreatment.