拟南芥转录辅激活因子ADA2b与染色质重塑因子SWI3B互作调控根发育的分子机制

During the root development, plant hormones, transcription factors and chromatin modifying factors regulate the transcription of root development related genes, and the roles of these factors exists a close inner link. Studies have shown that epigenetic modifications such as chromatin remodeling, histone acetylation and other epigenetic modifications may be involved in the regulation of gene expression mediated by these transcription factors, and play an important role in the root development. Our recent work showed that the transcriptional coactivator ADA2b，a member of the histone acetyltransferase SAGA complex，was a substrate for SUMOylation, and proved that ADA2b interact with SWI3B, a subunit of the SWI/SNF complex by yeast two hybrid，in vitro pull-down and FRET experiments, and SWI3B-RNAi transgenic plants appear short root phenotype. On this basis, this project will identify and study the biochemical mechanisms of the interaction between ADA2b and SWI3B and how to coordinated regulation of gene transcription, thereby affecting the molecular mechanism of root development, and hope to reveal the molecular mechanism of SUMOylation-mediated epigenetic regulation of root development, and also provide new theoretical basis for clarifing the root development of molecular regulatory networks.

根发育过程中植物激素、转录因子和染色质修饰相关因子转录调控根发育相关基因，同时这些因子的作用具有密切的内在联系。研究已表明染色质重塑、组蛋白乙酰化等表观遗传修饰参与这些转录因子所介导的基因表达调控，进而在根发育调控中起重要作用。本研究组在前期研究中证明了拟南芥转录辅激活因子ADA2b(组蛋白乙酰转移酶SAGA复合物亚基)是SUMO化底物；利用酵母双杂交、体外pull down和FRET等证明了AtADA2b与染色质重塑复合物SWI/SNF家族亚基SWI3B存在直接相互作用且SWI3B-RNAi转基因植株出现短根表型。本项目拟在此基础上结合细胞生物学、分子生物学和遗传学等方法，鉴定并研究ADA2b与染色质重塑因子SWI3B互作生化机制及如何协同调节基因转录，进而影响根发育的分子机制，揭示蛋白质SUMO化修饰介导表观遗传调控根发育分子机理，阐明根发育的分子调控网络。

根系作为植物最重要的营养器官之一，参与植株固定、水分和营养吸收及土壤微生物互作，在生长发育和环境应答中发挥重要功能。在农业生产上，发达健壮的根系是作物在正常条件下高产稳产的基础，更是作物在恶劣条件下生存的保障。因此，深入认识根系发育的基本规律是作物育种，特别是抗逆育种和养分高效育种的要基础。.植物根系的发育受多种因素调控，DNA损伤在植物根系发育过程中的功能研究较少。本项目围绕组蛋白乙酰化调控因子ADA2b介导主根发育的分子机制展开研究，主要阐明了ADA2b与染色质重塑因子SWI3B协同调控AtMMS21-SMC5/6复合体通过参与DNA修复介导主根发育的分子机理，并进一步表明ADA2b通过与小RNA加工因子CDC5互作参与DNA修复调控了主根的生长发育。此外，项目在探究AtMMS21调控主根发育的分子机制过程中发现生长素相关因子IAA17是AtMMS21的底物蛋白，AtMMS21通过调控生长素相关因子IAA17的SUMO化介导了拟南芥主根生长发育。.本项目的研究综合阐述了组蛋白乙酰化调控因子ADA2b介导主根发育的分子机制，增进了人们对DNA损伤修复的理解，为实践上培育抗逆高产的新品种作物奠定基础。