Natural variations of OsALDH2B1 contribute geographical adaptation to soil pH in rice

Enhancing the resilience of crops to ensure stable and high yields under adverse environmental conditions has long been a key objective in rice breeding, yet it remains challenging due to inherent trade-off mechanisms. Here, we report that OsALDH2B1 significantly improves both grain length and alkaline tolerance. Specifically, OsALDH2B1 enhances grain size by suppressing the expression of a grain size and alkaline tolerance related gene GS3 , while it positively regulates alkaline tolerance by reducing reactive oxygen species (ROS) accumulation in a manner that is partially independent of GS3 . Moreover, somatic embryogenesis receptor kinase like 1 (SERL1) phosphorylates and stabilizes OsALDH2B1 in response to alkaline stress. Additionally, the alkaline tolerant allele of OsALDH2B1 is predominantly distributed in high soil pH level regions. This study defines a previously unknown pathway by which the OsALDH2B1-centered module regulates alkaline tolerance for high soil pH value adaptation in rice.