Abstract
Escalating global warming threatens rice (Oryza sativa L.) growth and yield, making research into thermotolerance mechanisms imperative. OsLEML2, identified as a heat-responsive gene through microarray screening, was investigated in this study. It was found that overexpression of OsLEML2 reduces thermotolerance in transgenic plants. RT-qPCR analysis and physiological parameter measurements revealed that OsLEML2 disrupts reactive oxygen species homeostasis as well as suppresses HSF-HSP signaling. This gene affects the expression of auxin biosynthesis genes and catabolic genes, thereby influencing auxin homeostasis and regulating the heat tolerance of rice. Additionally, OsLEML2 potentially regulates thermotolerance by maintaining cellular auxin homeostasis through facilitating the efflux of excess auxin or its sequestration into the central vacuole, and by modulating pollen viability through the regulation of pollen reactive oxygen species levels. Collectively, our functional characterization has identified OsLEML2 as a negative regulatory factor in heat stress responses, providing a potential genetic target for enhancing thermotolerance in crops via molecular breeding strategies. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12284-025-00856-7.