拟南芥转录因子AtMYB73通过与成花素FT相互作用来调控开花时间

高等植物开花时间调控，对生育期、产量和品质都有重大影响，因此对植物生存和人类粮食安全都非常重要。研究开花时间的分子机制对农业生产具有重要意义；前期我们研究发现成花素FT和抑制成花素TFL1基因竞争性调控下游基因影响植物开花，但FT和TFL1之间的调控关系还不清楚。本项目通过筛选TFL1下游基因，发现拟南芥MYB73转录因子，在其缺失功能时提早开花。myb73突变体中FT转录本上升，特异性诱导MYB73能使FT表达下调。免疫共沉淀MYB73-GFP发现其与FT基因有结合，ft myb73双突早花消失。MYB73与三个同源基因MYB44/70/77有蛋白互作，一组三突比myb73单突开花更早。本项目拟深入研究拟南芥MYB73的表达模式，结合生物大数据技术RNAseq, ChIPseq 和蛋白质质谱，最终阐明MYB73如何根据内外环境通过TFL1-MYB73-FT路径精准调控开花时间的分子机制。

The changes of flowering time in high plants have an extensive impact on the reproductive growth period, subsequently affecting the quantity and quality of the yield, which is of great importance for plant survival and human food security. Our previous studies on florigen FT and anti-florigen TFL1 uncovered their critical roles of flowering time regulation by the antagonistic control of downstream genes. However, whether there are underlying regulatory mechanisms between FT and TFL1 is still unknown. In this project, by large-scale screening of TFL1 targets, one transcription factor, AtMYB73, was identified as a repressor of flowering time, as the loss-of-function mutation showed an early-flowering phenotype under long days. The expression of FT was significantly increased in atmyb73 mutant and the specific induction of AtMYB73 could down-regulate FT expression. Chromatin immunoprecipitation (ChIP) of AtMYB73-GFP found that AtMYB73 bound to the FT gene. In addition, ft atmyb73 double mutant blocked the early flowering of atmyb73. AtMYB73 had protein-protein interactions with other three MYB proteins AtMYB44/70/77, and one of triple mutants flowered earlier than atmyb73. This project aims to show detailed expression patterns of AtMYB73, to profile RNA-seq and ChIP-seq biodata, and to perform in-depth proteomic analyses. All in all, how AtMYB73 comprehensively and tightly regulate flowering time in response to endogenous and environmental factors, and how the TFL1-AtMYB73-FT regulon is accurately executed would be crystally clarified.