Zheng Ming, Wang Yihua, Wang Yunlong, Wang Chunming, Ren Yulong, Lv Jia, Peng Cheng, Wu Tao, Liu Kai, Zhao Shaolu, Liu Xi, Guo Xiuping, Jiang Ling, Terzaghi William, Wan Jianmin
State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, 210095, China.
National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
New Phytol. 2015 Jun;206(4):1476-90. doi: 10.1111/nph.13318. Epub 2015 Feb 10.
Floral organ identity in plants is controlled by floral homeotic A/B/C/D/E-class genes. In Arabidopsis thaliana, several epigenetic repressors that regulate these floral organ identity genes have been characterized. However, the roles of epigenetic factors in rice floral development have not been explored in detail. Here, we report the identification and functional characterization of a rice epigenetic repressor, DEFORMED FLORAL ORGAN1 (DFO1) gene, which causes abnormal floral morphology when mutated. We isolated dfo1 by mapping, and confirmed its function by rescue experiments, combined with genetic, cytological and molecular biological analysis. We showed that DFO1 is constitutively expressed and encodes a nuclear-localized protein. Mutation of DFO1 causes the ectopic expression of C-class genes in the dfo1-1 mutant, and overexpression of OsMADS58, a C-class gene, phenocopies the dfo1 mutants. In vitro and in vivo experiments demonstrated that DFO1 interacts with the rice polycomb group (PcG) proteins (OsMSI1 and OsiEZ1). Remarkably, trimethylation of histone H3 lysine 27, a mark of epigenetic repression, is significantly reduced on OsMADS58 chromatin in the dfo1-1 mutant. Our results suggest that DFO1 functions in maintaining rice floral organ identity by cooperating with PcG proteins to regulate the H3K27me3-mediated epigenetic repression on OsMADS58.
植物花器官的特征由花同源异型A/B/C/D/E类基因控制。在拟南芥中，已经鉴定出几种调控这些花器官特征基因的表观遗传抑制因子。然而，表观遗传因子在水稻花发育中的作用尚未得到详细研究。在此，我们报道了一个水稻表观遗传抑制因子——畸形花器官1（DFO1）基因的鉴定和功能表征，该基因在发生突变时会导致花形态异常。我们通过定位分离出了dfo1，并通过拯救实验以及遗传、细胞学和分子生物学分析证实了其功能。我们发现DFO1组成型表达并编码一种定位于细胞核的蛋白质。DFO1的突变导致dfo1-1突变体中C类基因的异位表达，而过表达C类基因OsMADS58会模拟dfo1突变体的表型。体外和体内实验表明，DFO1与水稻多梳蛋白组（PcG）蛋白（OsMSI1和OsiEZ1）相互作用。值得注意的是，在dfo1-1突变体的OsMADS58染色质上，组蛋白H3赖氨酸27的三甲基化（一种表观遗传抑制标记）显著减少。我们的结果表明，DFO1通过与PcG蛋白合作，调节OsMADS58上由H3K27me3介导的表观遗传抑制，从而在维持水稻花器官特征中发挥作用。
