MdWRKY126转录因子在苹果果实有机酸积累中的功能和转录调控机制

酸度是控制果实风味品质的重要因素之一。研究表明苹果中Ma1基因是控制果实酸度的关键基因，其ma1纯合型通常表现为低酸。项目研究前期，申请人从苹果种质资源中筛选出ma1纯合型高酸样本‘宝斯库普’，通过对果实不同发育时期转录组测序、qRT-PCR以及遗传转化等方法筛选并鉴定出酸度控制基因MdWRKY126，但该基因调控苹果果实酸度的分子机制目前尚不清楚。本项目拟在此研究基础上，利用转录组测序、ChIP-seq、酵母单杂交及EMSA等筛选并鉴定MdWRKY126下游调控靶基因，并利用基因表达、亚细胞定位及遗传转化等试验验证靶基因生物学功能。同时基于酵母单双杂交系统、ChIP、EMSA及BiFC等筛选并验证MdWRKY126基因上游调控基因及其互作蛋白。本项目的开展不仅能够解析基于MdWRKY126基因的苹果果实酸度分子调控机制，同时对苹果果实品质遗传改良具有重要的理论意义及生产指导价值。

Acidity is one of the main determinants of the fruit organoleptic quality. Fruit acidity was determined by Ma1 gene, and apple accessions containing homolozygous ma1 (ma1ma1) exhibit low acidity in fruits. However, we found that a cultivar ‘Belle de Boskoop’, which contains homolozygous ma1 (ma1ma1) at Ma1 locus, accumulates high level of malate in fruits. Fruit transcriptome analysis for ‘Belle de Boskoop’ was performed to identify genes responsible for apple fruit acidity. Together with qRT-PCR and transgenetic analysis, one gene, designated MdWRKY126, was found could determine fruit acidity. However, the mechanism underling how MdWRKY126 regulate fruit acidy remains unclear. Based on our previous study, the downstream targets of MdWRKY126 are going to screen and identify by transcript sequencing, ChIP-sequencing, yeast one-hybrid and EMSA. In addition, gene expression profile, subcellular localization and transgenic approaches are also utilized to confirm the biological function of targeted genes. Similarly, we will carry out yeast hybrid system, EMSA and BiFC to identify the upstream targets of MdWRKY126 and its corresponding interactive protein. The process of our project is not only helpful to clarify the mechanism underlying apple fruit organic acid accumulation which regulated by MdWRKY126, but will also provide theoretical and practical knowledges for the genetic improvement of fruit quality in apple breeding programs.