CURVED CHIMERIC PALEA 1 encoding an EMF 1‐like protein maintains epigenetic repression of O s MADS 58 in rice palea development

• Published in: The Plant journal : for cell and molecular biology Vol. 82; no. 1; pp. 12 - 24
• Main Authors: Yan, Dawei, Zhang, Xiaoming, Zhang, Lin, Ye, Shenghai, Zeng, Longjun, Liu, Jiyun, Li, Qun, He, Zuhua
• Format: Journal Article
• Language: English
• Published: 01.04.2015
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/tpj.12784

Summary Floral organ specification is controlled by various MADS ‐box genes in both dicots and monocots, whose expression is often subjected to both genetic and epigenetic regulation in Arabidopsis thaliana . However, little information is known about the role of epigenetic modification of MADS ‐box genes during rice flower development. Here, we report the characterization of a rice gene, CURVED CHIMERIC PALEA 1 ( CCP 1 ) that functions in palea development. Mutation in CCP 1 resulted in abnormal palea with ectopic stigmatic tissues and other pleiotropic phenotypes. We found that O s MADS 58 , a C‐class gene responsible for carpel morphogenesis, was ectopically expressed in the ccp1 palea, indicating that the ccp1 palea was misspecified and partially acquired carpel‐like identity. Constitutive expression of O s MADS 58 in the wild‐type rice plants caused morphological abnormality of palea similar to that of ccp1 , whereas O s MADS 58 knockdown by RNA i in ccp1 could rescue the abnormal phenotype of mutant palea, suggesting that the repression of O s MADS 58 expression by CCP 1 is critical for palea development. Map‐based cloning revealed that CCP 1 encodes a putative plant‐specific EMBRYONIC FLOWER 1 ( EMF 1)‐like protein. Chromatin immunoprecipitation assay showed that the level of the H3K27me3 at the O s MADS 58 locus was greatly reduced in ccp1 compared with that in the wild‐type. Taken together, our results show that CCP 1 plays an important role in palea development through maintaining H3K27me3‐mediated epigenetic silence of the carpel identity‐specifying gene O s MADS 58 , shedding light on the epigenetic mechanism in floral organ development. Significance Statement The rice CCP1 gene encodes an EMF1‐like protein that functions in palea development through maintaining H3K27me3‐mediated epigenetic silencing a carpel identity‐specifying gene OsMADS58. The study identified an important component of rice Polycomb repressive complex (PRC) and sheds light on the mechanism of epigenetic modification of floral organ development in plants.