OsRELA Regulates Leaf Inclination by Repressing the Transcriptional Activity of OsLIC in Rice.

Leaf angle is one of the most important agronomic traits in rice, and changes in leaf angle can alter plant architecture to affect photosynthetic efficiency and thus determine grain yield. Therefore, it is important to identify key genes controlling leaf angle and elucidate the molecular mechanisms to improve rice yield. We obtained a mutant with reduced leaf angle in rice by EMS mutagenesis, and map-based cloning revealed that encodes a protein of unknown function. Coincidentally, () was reported in a previous study with the same gene locus. analysis revealed that is involved in regulating the expression of and family genes. Biochemical and genetic analyses revealed that OsRELA is able to interact with OsLIC, a negative regulator of BR signaling, through its conserved C-terminal domain, which is essential for OsRELA function in rice. The binding of OsRELA can activate the expression of downstream genes repressed by OsLIC, such as , a positive regulator of leaf inclination in rice. Therefore, our results suggest that OsRELA can act as a transcriptional regulator and is involved in the regulation of leaf inclination by regulating the transcriptional activity of OsLIC.