• 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 conditions. HES1 encoded a UDP-N-acetylglucosamine pyrophosphorylase, which had UGPase enzymatic activity. RNA sequencing analysis showed that photosystem-related genes were differentially expressed in the hes1 mutant at different temperatures, indicating that HES1 plays essential roles in maintaining chloroplast function. HES1 expression was induced under high temperature conditions.
• Furthermore, loss-of-function of HES1 affected heat shock factor 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 at high temperature. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and comet experiments indicated that the hes1 underwent more severe DNA damage at high temperature. The determination of chlorophyll content and chloroplast ultrastructure showed that more severe photosystem defects occurred in the hes1 mutant under high temperature conditions.
• This study reveals that HES1 plays a key role in adaptation to high-temperature stress in rice.

中文翻译：

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UDP-N-乙酰氨基葡萄糖焦磷酸化酶提高水稻高温存活率

• 高温胁迫抑制正常的细胞过程并导致植物的异常生长和发育。然而，水稻（Oryza sativa）应对高温的机制尚不完全清楚。
• 在本研究中，我们鉴定了水稻高温增强病斑1 ( hes1 ) 突变体，该突变体在高温条件下表现出更大、更密集的坏死斑。HES1编码具有UGPase酶活性的 UDP- N-乙酰氨基葡萄糖焦磷酸化酶。RNA测序分析表明，光合相关基因的差异表达HES1在不同温度下的突变，表明HES1在维持叶绿体功能至关重要的作用。在高温条件下诱导HES1表达。
• 此外，HES1的功能丧失影响热休克因子的表达，其突变表现出对高温的更大脆弱性。多项实验表明，hes1突变体在高温下会产生较高的活性氧积累。末端脱氧核苷酸转移酶 dUTP 缺口末端标记 (TUNEL) 和彗星实验表明hes1在高温下受到更严重的 DNA 损伤。叶绿素含量和叶绿体超微结构的测定表明，hes1突变体在高温条件下发生了较严重的光系统缺陷。
• 该研究表明，HES1在水稻适应高温胁迫中起关键作用。