水稻组蛋白去乙酰化基因OsSAP30s通过光周期途径调控抽穗期的功能研究

Heading date in rice is a critical agronomic trait that effects potential yield, growing season and regional adaptability. The day length is a key seasonal cue for regulating heading date in rice，a facultative short-day plant. The systemic flowering signal (florigen) encoded by Hd3a and RFT1 to provoke the floral transition. The Hd3a and RFT1 expression level play the essencial role to ensure the timely transition in rice. At present, the mechanism of Hd3a/RFT1 expression in response to the day-length cue to set a proper heading date remains elusive. Here, we have identified three relatives of the yeast ScSAP30s named OsSAP30a、OsSAP30b and OsSAP30c in rice, and mutants show early heading. OsSAP30s have the similarity expression patter with Hd1, and deacetylated function in vitro. OsSAP30s could associate with other four deacetylation-related protein, HDA9, HDA19, SNL2 and SAP18. These results indicted these gene possible rhythmically activate Hd3a/RFT1 expression to regulated floral transition. Study the role of OsSAP30s via complex identification，rhythm expression，ChIP binding analysis will uncover a periodic histone deacetylation mechanism to sets the correct level of Hd3a expression for the proper heading date in rice.

抽穗期是影响水稻产量、栽培地区和栽培时间的重要农艺性状，光照长度作为影响抽穗的重要环境信号受到光周期途径的调控。光周期途径核心开花素基因Hd3a/RFT1 的适量表达水平是水稻适时抽穗、保证产量的关键，但如何响应光周期昼夜信号控制水稻“适时”抽穗的机制尚需进一步研究。我们鉴定了3个水稻乙酰化基因OsSAP30s，全基因组关联分析显示3个基因和抽穗期具有相关性，突变体呈现早花表型；进一步研究发现OsSAP30s蛋白具有去乙酰化的功能，可以和4个水稻组蛋白去乙酰化相关蛋白形成复合体，具有和光周期途径关键基因Hd1类似的24h节律性表达模式，这些结果显示OsSAP30s基因可能在响应光照长度调控水稻抽穗期方面起着重要作用。本项目希望通过研究OsSAP30s及形成的复合体 “测量和平衡”开花素基因节律性表达的模式，揭示控制水稻“适时”抽穗的分子机制，为水稻研究及育种提供理论依据、基因资源和和材料。

抽穗期是影响水稻产量、栽培地区和栽培时间的重要农艺性状，表观遗传是其中重要的调节因子。组蛋白去乙酰化复合体（HDAC）功能是去除组蛋白乙酰基，从而导致染色质结构浓缩并抑制基因表达。目前，HDAC复合体调节水稻抽穗期的生物学机制仍不清楚。本项目在水稻中鉴定了酵母SAP30的直系同源基因OsSAP30s，与抽穗时间密切相关。水稻SAP30s突变后，在短日照条件下（SDs）影响开花时间。OsSAP30s功能缺失改变了节律基因Hd1的光周期节律，抑制了Hd3a的表达。此外，在水稻中OsSAP30s也可以直接与其他HDAC复合体成员OsSAP18、OsHDAC2等相互作用，形成HDAC复合体。本项目首次发现了组蛋白去乙酰化复合体成员SAP30s介导的组蛋白去乙酰化动态修饰调控水稻抽穗期的分子机理，为表观遗传调控水稻抽穗期的理论研究提供了重要基因资源和材料。