黄瓜“花打顶”基因CsTFL1的功能及其分子调控机制研究

"Terminal Flower" is a major physiological disease in winter-spring greenhouse cucumber cultivation in China. It was proved that low temperature and poor light in greenhouse would lead to clustered inflorescence on the shoot apex, stagnation of vegetative growth, and terminal flowers phenomenon occurs. The worst effect of "Terminal Flower" was resulting in a substantial decline in yield and quality. To breed new cucumber varieties resistance to low temperature and poor light is a fundamental way to solve this problem , but it depends on elucidating the genetic mechanisms of "Terminal Flower" phenomenon. But the genetic research of terminal flower is too few to apply. Prior to this study, we've done fine mapping of terminal flower gene(Cstfl1) by using of one cucumber mutant and initially concluded that loss of function of CsTFL1 led to "Terminal Flower". But the function and regulatory mechanism of CsTFL1 in cucumber is not clear. This project focus on reverse genetic research on CsTFL1,it'll test genetic complementation in Cucumber and Arabidopsis, and analyze the expression patterns of CsTFL1, in addition, to screen the close relative genes of CsTFL1 by RNA-SEQ and Y1H systems. This study is intend to preliminarily construct the molecular regulatory pathways of CsTFL1. This study will elucidate the functional and molecular regulation pattern of CsTFL1, to provide new ideas of solving the terminal flower problem, and to provide scientific basis for breeding new germplasms to resistance low temperature and poor light in Cucumis Sativus L. Our findings both provide a reference for molecular genetics research on "Terminal Flower" in Cucurbitaceae , and can provide a scientific basis for conducting research to breed new varieties resistance to low temperature and poor light.

“花打顶”是严重影响我国冬春季黄瓜设施生产的主要生理病害。研究表明：设施低温弱光容易引起茎尖着生花序、营养生长停滞的花打顶现象，造成产量和品质大幅下降。培育耐低温弱光品种是解决这一问题的根本途径，而阐明花打顶的遗传机理将有助于耐低温弱光品种的培育。本项目前期利用黄瓜“花打顶”突变体和图位克隆技术，克隆了控制花打顶的基因Cstfl1，并推断花打顶是由于CsTFL1发生突变、功能丧失而引起的。本项目拟采用转基因技术转化黄瓜和拟南芥，对CsTFL1的功能进行遗传互补验证；在此基础上，利用RNA-SEQ对突变体和转基因植株进行转录组分析，筛选与CsTFL1相关的差异表达基因；同时，利用Y1H酵母单杂交技术筛选与CsTFL1互作的关键蛋白因子，构建CsTFL1调控花打顶的基因网络。该研究结果不仅可为葫芦科作物的花打顶遗传机理剖析提供参考，而且可为培育耐低温弱光的新品种提供科学依据。

“花打顶”是严重影响我国冬春季黄瓜设施生产的主要生理病害。本项目前期利用发现的一株黄瓜天然“花打顶”突变体，图位克隆了控制花打顶的重要基因CsTFL1，并推测该基因发生突变后功能受损引起了黄瓜花打顶。本项目对CsTFL1的功能进行了遗传互补验证，发现CsTFL1基因可以互补拟南芥tfl1突变体表型，黄瓜CsTFL1 -RNAi植株表现出花打顶现象，证明黄瓜CsTFL1基因是产生花打顶的关键基因；同时，本研究发现CsTFL1调控花打顶主要依靠其重要拮抗基因，CsFT来行驶功能。CsFT在花打顶材料的茎尖生长点部位表达较高，而CsFT可与开花转录因子CsFD进行互作，推测该互作是激活下游开花基因形成花打顶的关键。其次，本研究利用转录组分析花打顶突变体、CsTFL1 -RNAi植株及外源物质和环境诱导产生的花打顶黄瓜茎尖发现，下游开花基因CsSOC1和CsAP1也表达上调，推测其为参与花打顶形成的关键基因。另外，本研究获得的CsTFL1基因序列变异分子标记可作物抗花打顶材料筛选的重要依据，目前已应用于新种质创制中。总之，本研究初步证实了黄瓜CsTFL1调控花打顶的遗传功能，挖掘了CsTFL1/CsFT-CsSOC1/CsAP1调控花打顶形成的分子路径。本研究成果黄瓜抗花打顶育种提供重要支撑，也可为其他瓜类作物解决花打顶难题提供重要参考。