KRN4调控玉米穗行数的分子机理研究

Kernel row number (KRN) is an important yield component of maize. Previously, we have identified and cloned a major KRN QTL KRN4, and the distally regulatory role of KRN4 on the expression of important maize inflorescence genes Unbranched3 (UB3) and the negative control of KRN by UB3 have been proposed based on the previous results. On behalf of previous results and related published studies, two possible mechanisms of the regulation of UB3 expression by KRN4 were raised. Firstly, KRN4, as an enhancer, could cis regulate UB3 expression. Secondly, the 1.2-Kb transposons insertion and deletion polymorphisms within KRN4 could express siRNA or be the target of siRNA, and then regulate the UB3 expression by the small mediated epigenetic modification. To validate this hypothesis, the KRN4 mutant analysis, the transient assays in protoplasts, chromosome conformation capture technology, siRNA expression analysis and so on will be employed in the present project. Moreover, the yeast one-hybrid experiment will also be used to screen the factors those media the interaction between KRN4 and UB3. The research purpose of this project is to dissect the molecular mechanisms of the distally regulatory role of KRN4 on UB3 expression, which will help us further understand the genetic basis and molecular mechanisms underlying the natural variation of kernel row number of maize, and it is also helpful for guiding the application of KRN4 in maize breeding.

穗行数是玉米重要的产量构成因子。本项目前期研究鉴定并克隆了一个控制玉米穗行数自然变异的主效QTL KRN4,并证实KRN4通过远距离调控玉米花序发育基因Unbranched3(UB3),调控玉米穗行数的数量变异。基于前期研究结果及前人积累的相关理论基础,我们假设KRN4可能通过两种机制调控UB3表达:1)KRN4作为增强子顺式调控UB3表达;2)KRN4可能表达siRNA或作为其靶点,通过表观修饰反式调控UB3表达。本项目拟通过KRN4突变体遗传分析、原生质体瞬时表达、染色体构象捕获、siRNA分析及表观修饰的检测等方面研究,探索KRN4调控UB3的作用方式。并利用酵母单杂等手段,筛选并验证介导KRN4与UB3互作的关键因子。以期解析KRN4的远距离调控UB3表达的分子机理。本项目研究结果有助于我们深入认知玉米穗行数形成的遗传基础和分子调控机理,对KRN4位点的育种应用也具有重要的指导意。

穗行数是玉米重要的产量构成因子。本项目前期研究鉴定并克隆了一个控制玉米穗行数自然变异的主效QTL KRN4,并证实KRN4通过远距离调控玉米花序发育基因Unbranched3(UB3),调控玉米穗行数的数量变异。本项目通过KRN4突变体遗传分析、原生质体瞬时表达、染色体构象捕获等方面研究,探索KRN4调控UB3的作用方式，探索介导KRN4与UB3互作的关键因子。通过各项研究证实KRN4作为增强子元件。同时筛选并验证了UB2、OBF1和OBF4，作为反式因子复合体，结合KRN4，通过染色质空间交互作用，空间上靠近并作用于UB3启动子区域，介导KRN4-UB3启动子的互作，顺式调控UB3基因表达量。本项目解析了KRN4的远距离调控UB3表达的分子机理，有助于我们深入认知玉米穗行数形成的遗传基础和分子调控机理,对KRN4位点的育种应用也具有重要的指导意。