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Summary: Grain number is an important agronomic trait. We investigated the roles of chromatin interacting factor Oryza sativa VIN3‐LIKE 2 (OsVIL2), which controls plant biomass and yield in rice. Mutations in OsVIL2 led to shorter plants and fewer grains whereas its overexpression (OX) enhanced biomass production and grain numbers when compared with the wild type. RNA‐sequencing analyses revealed that 1958 genes were up‐regulated and 2096 genes were down‐regulated in the region of active division within the first internodes of OX plants. Chromatin immunoprecipitation analysis showed that, among the downregulated genes, OsVIL2 was directly associated with chromatins in the promoter region of CYTOKININ OXIDASE/DEHYDROGENASE2 (OsCKX2), a gene responsible for cytokinin degradation. Likewise, active cytokinin levels were increased in the OX plants. We conclude that OsVIL2 improves the production of biomass and grain by suppressing OsCKX2 chromatin. [ABSTRACT FROM AUTHOR]

Flower organ patterning is accomplished by spatial and temporal functioning of various regulatory genes. We previously reported that Oryza sativa VIN3-LIKE 2 (OsVIL2) induces flowering by mediating the trimethylation of Histone H3 on LFL1 chromatin. In this study, we report that OsVIL2 also plays crucial roles during spikelet development. Two independent lines of T-DNA insertional mutants in the gene displayed altered organ numbers and abnormal morphology in all spikelet organs. Scanning electron microscopy showed that osvil2 affected organ primordia formation during early spikelet development. Expression analysis revealed that OsVIL2 is expressed in all stages of the spikelet developmental. Transcriptome analysis of developing spikelets revealed that several regulatory genes involved in that process and the formation of floral organs were down-regulated in osvil2. These results suggest that OsVIL2 is required for proper expression of the regulatory genes that control floral organ number and morphology. [ABSTRACT FROM AUTHOR]