벼의 개화 시기와 수량을 조절하는 chromatin remodeling factor의 기능 연구
- 벼의 개화 시기와 수량을 조절하는 chromatin remodeling factor의 기능 연구
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- Post-translational modification is a key mechanism regulating protein function. Post-translational modifications of nucleosomal core histones play roles in basic biological processes via altering chromatin structure and creating target sites for proteins acting on chromatin. Molecular genetic studies with Arabidopsis have verified several epigenetic factors that regulate flowering time. However, the roles of chromatin remodeling factors in developmental processes have not been well explored in rice. Here, I identified a chromatin remodeling factor, OsVIL2 (Oryza sativa VIN3-LIKE 2), that promotes flowering. OsVIL2 contains a plant homeodomain (PHD) finger, which is a conserved motif of histone binding proteins. Insertion mutations in OsVIL2 caused late flowering under both long and short days. In osvil2 mutants OsLFL1 expression was increased but that of Ehd1, Hd3a, and RFT1 was reduced. I demonstrated that OsVIL2 is bound to native histone H3 in vitro. Chromatin immunoprecipitation analyses showed that OsVIL2 was directly associated with OsLFL1 chromatin. I also observed that trimethylation of histone 3 lysine 27 (H3K27me3) was significantly enriched on OsLFL1 chromatin in WT but that this enrichment was diminished in the osvil2 mutants. These results indicated that OsVIL2 epigenetically represses OsLFL1 expression. I showed that OsVIL2 physically interacted with OsEMF2b, a component of polycomb repression complex 2 (PRC2). As observed from osvil2, a null mutation of OsEMF2b caused late flowering by increasing OsLFL1 expression and decreasing Ehd1 expression. Thus, I conclude that OsVIL2 functions together with PRC2 to induce flowering by repressing OsLFL1. In addition, I showed that overexpression of OsVIL2 affected plant height and number of spikeltes per panicle. OsVIL2 overexpression (OsVIL2-OX) plants exhibited the phenotypes of longer internodes and thicker stems than control plants. Histochemical analysis revealed that the OsVIL2-OX plant cells were smaller and had more cells. The transgenic plants have a suitable architecture to obtain high yield.
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