OsPEX5 regulates rice spikelet development through modulating jasmonic acid biosynthesis

Summary Spikelet is the primary reproductive structure and a critical determinant of grain yield in rice. The molecular mechanisms regulating rice spikelet development still remain largely unclear. Here, we report that mutations in Os PEX 5 , which encodes a peroxisomal targeting sequence 1 ( PTS 1) receptor protein, cause abnormal spikelet morphology. We show that Os PEX 5 can physically interact with Os OPR 7, an enzyme involved in jasmonic acid ( JA ) biosynthesis and is required for its import into peroxisome. Similar to Ospex5 mutant, the knockout mutant of Os OPR 7 generated via CRISPR ‐Cas9 technology has reduced levels of endogenous JA and also displays an abnormal spikelet phenotype. Application of exogenous JA can partially rescue the abnormal spikelet phenotype of Ospex5 and Osopr7 . Furthermore, we show that Os MYC 2 directly binds to the promoters of Os MADS 1 , Os MADS 7 and Os MADS 14 to activate their expression, and subsequently regulate spikelet development. Our results suggest that Os PEX 5 plays a critical role in regulating spikelet development through mediating peroxisomal import of Os OPR 7, therefore providing new insights into regulation of JA biosynthesis in plants and expanding our understanding of the biological role of JA in regulating rice reproduction.