Recently, the team of academician Liu Yaoguang from the school of life sciences and the State Key Laboratory of South China Agricultural University published a report entitled”rice osubr7 modulates plant height by regulating histone H2B Mo” in the new botanical journal plant communications (impact factor 8.625, biological zone 1)Research paper on”noubiquidation and cell promotion” (paper link:https://doi.org/10.1016/j.xplc.2022.100412 ）。
Rice (Oryza sativa L.) is one of the most important food crops in the world, and it is also a model organism for monocotyledon genome and genetic research. Plant height, as an important agronomic trait of crop lodging resistance and high-yield breeding, is also one of the important factors affecting rice yield. Therefore, in-depth study on the expression regulation and action mechanism of rice semi dwarf gene can provide a theoretical basis for improving the molecular mechanism of rice plant height development and breeding improvement. In this study, a new rice semi dwarf mutant osubr7 and its related gene osubr7 were found, which encodes an E3 ubiquitin ligase of monoubiquitinated histone H2B (h2bub1). H2bub1 is a common and important epigenetic modification of histones in chromatin, which is closely related to the regulation of gene transcription activity in eukaryotes. However, the regulatory role of h2bub1 in plant height development is still rarely studied.
Through a series of biochemical experiments, this study proved that osubr7, as a new E3 ligase, catalyzes the monoubiquitination of H2B in rice and is an epigenetic regulator of many gene loci related to cell proliferation and organ development. In wild-type rice, osubr7 specifically binds H2B in some chromatin regions and is monoubiquitinated at k148. This process is performed by osubc18 as the specific E2 ubiquitin binding enzyme of osubr7. By changing the chromatin status of these gene loci, normal transcription and cell cycle processes are maintained to ensure normal development. However, in osubr7 mutant plants, the loss of function of osubr7 resulted in the reduction of h2bub1 level at the target gene site, thereby reducing the expression level of the target gene. The inhibited cell cycle process will lead to the shortening of internodes, resulting in the reduction of plant height of osubr7 mutant. This new plant h2bub1 modification mechanism mediated by osubr7 not only extends the known functions of the ubr7 family in eukaryotes, but also can be used as an undeveloped epigenetic resource to improve plant type and lodging resistance traits of crops.
Academician Liu Yaoguang and Associate Professor Chu zhizhan of the College of life sciences are the co authors of the paper. Liu Yaoguang, academician of the College of life sciences, has graduated from the research group, and Zheng Yangyi is the first author of the paper. The research was supported by the National Natural Science Foundation of China, the national key research and development program and the natural science foundation of Guangdong Province.