VALs蛋白调控拟南芥开花的遗传机制

Flowering is an important physiological phenomenon in the growth and reproduction of higher plants and this process is controlled by a complex genetics net. In Arabidopsis the FVE-FLD-HDA5-HDA6 complexes decrease the level of Histone acetylation and methylation of FLC locus, a main flowering repressor, and then repress the transcriptional expression of FLC and activate flowering, however the mechanism of the FVE-FLD-HDA5-HDA6 complexes to recognize and be recruited to the FLC locus is unclear. In the project previously study we identified two plant-specific B3-domain VP1/ABI3-LIKE (VAL) proteins could recognize and bind the nucleating region of FLC locus, and VAL proteins interact with FVE in yeast. Through this project we aim to systematic analysis the histone deacetylation and demethylation modification in FLC locus through VAL proteins and the response of binding to the FLC locus between VAL proteins and the components of FVE-FLD-HDA5-HDA6 complexes, and to elucidate the molecular mechanism of FLC transcriptional expression affected by VAL proteins through the FVE-FLD-HDA5-HDA6 complexes. Prospective outputs from this project would reveal the molecular contact between the histone modification complex and its target sites in Arabidopsis, and thus maybe provide theoretical and practical basis of genetics improvement in higher plant.

开花是高等植物生殖生长过程中重要的生理现象，其过程受到复杂的遗传网络调控。拟南芥中FVE-FLD-HDA5-HDA6复合体通过降低开花抑制因子FLC位点组蛋白乙酰化及甲基化水平，从而抑制FLC的转录，促进开花，然而FVE-FLD-HDA5-HDA6复合体如何识别并被招募至FLC位点的分子机理还不清楚。本项目前期的研究鉴定出植物特有的含B3结构域的VALs蛋白可以特异识别并结合到FLC位点成核区，同时酵母双杂交确定VALs与FVE互作。本项目拟通过系统分析VALs蛋白对FLC位点组蛋白乙酰化和甲基化水平的调控及与FVE-FLD-HDA5-HDA6复合体各成员结合到FLC位点的相互影响，明确VALs蛋白通过FVE-FLD-HDA5-HDA6复合体抑制FLC转录调控的分子机理。本项目的研究结果将揭示拟南芥中组蛋白修饰复合体与靶位点之间的分子联系，并有可能为高等植物的遗传改良提供理论及实践基础。

本项目是基于我们前期工作鉴定出植物特有的含B3结构域的VALs蛋白可以特异识别并结合到FLC位点成核区，继续探究FVE-FLD-HDA5-HDA6组蛋白去乙酰化及甲基化复合体是否通过VALs蛋白被招募至靶基因位点FLC，引起FLC位点染色质重建，调控FLC基因表达。项目主要是通过多种蛋白互作方法验证VALs蛋白是否与FVE-FLD-HDA5-HDA6蛋白复合体成员互作；再通过遗传学方法及分子生物学方法验证FVE-FLD-HDA5-HDA6蛋白复合体是否通过VALs蛋白被招募至FLC位点并影响FLC位点的组蛋白修饰水平的改变，从而调控拟南芥开花。通过本项目研究，取得的重要结果为：体内体外生化实验证明VAL1/VAL2与FVE及HDA6互作；遗传学实验确定双突变体val1fve及val2fve比单突变体fve更晚开花，且FLC表达水平更高；通过CHIP-PCR确定FVE被招募至FLC位点及引起FLC位点的去乙酰化及甲基化水平均受VALs蛋白的影响。本项目的研究结果明确了VALs蛋白与FVE-FLD-HDA5-HDA6复合体共同抑制FLC转录调控的分子机理，也揭示了拟南芥中组蛋白修饰复合体与靶基因之间的分子联系，为高等植物的分子遗传改良提供理论及实践基础。