UDP-N-acetylglucosamine pyrophosphorylase enhances rice survival at high temperature.

• High-temperature stress inhibits normal cellular processes and results in abnormal growth and development in plants. However, the mechanisms by which rice (Oryza sativa) copes with high temperature are not yet fully understood. • In this study, we identified a rice high temperature enhanced lesion spots 1 (hes1) mutant, which displayed larger and more dense necrotic spots under high temperature. HES1 encoded a UDP-N-acetylglucosamine pyrophosphorylase, which had the UGPase enzymatic activity. RNA sequencing analysis showed that photosystem-related genes were differentially expressed in the hes1 mutant under different temperatures, indicating that HES1 plays essential roles in maintaining chloroplast function. HES1 expression was induced under high temperature. • Furthermore, loss of function of HES1 affected the HSFs expression and its mutation exhibited greater vulnerability to high temperature. Several experiments revealed that higher accumulation of reactive oxygen species occurred in the hes1 mutant under high temperature. TUNEL and comet experiments indicated that the hes1 undergo more severe DNA damage under high temperature. The determination of chlorophyll content and chloroplast ultrastructure showed more severe photosystem-defects occurred in the hes1 mutant under high temperature. • This study reveals that HES1 plays a key role in adaptation to high-temperature stress in rice.