Serine protease NAL1 exerts pleiotropic functions through degradation of TOPLESS-related corepressor in rice

Abstract NAL1 ( NARROW LEAF 1 ) is a breeding-valuable pleiotropic gene that affects multiple agronomic traits in rice, but the molecular mechanism is largely unclear. Here, we report that NAL1 is a serine protease and displays a novel hexameric structure whose formation is mediated by ATP-containing positively charged pocket at the N-terminal region. Moreover, we identified TOPLESS-related corepressor OsTPR2 involved in multiple growth and development processes as the substrate of NAL1. We found that NAL1 degraded OsTPR2, thus modulating the expression of downstream genes related to hormone signaling pathways, eventually achieving its pleiotropic physiological function. An elite allele NAL1 A originated from wild rice could increase grain yield. Furthermore, the NAL1 homologs in different crops have a similar pleiotropic function to NAL1 . Our study uncovers a NAL1-OsTPR2 regulatory module and provides gene resources for the design of high-yield crops.