IAA调控棉纤维起始与分化发育的表观遗传机制研究

Cotton is the most important fiber crops in the world. Cotton fiber is single fiber formed by ovule epidermal cells through differentiation and development. Therein, the initial differentiation phase is an important period affecting the yield and quality of cotton fiber, while it is significantly influenced by IAA but so far lacking the systematic study on the molecular regulation mechanism. This project intends to take iaaM transgenic genotype IF11 and its receptor J - 14 which importantly differ in endogenous auxin content of ovule as materials, employing a new high flux-Seq small RNA-Seq and Genome-wide bisulfite sequencing (WGBS), using the methods such as SL - RTPCR and 5 '- RLM – RACE, combining the analysis e.g. miRDeepFinder and RepeatMasker etc., to identify the miRNAs expression and the characteristics of the DNA methylation in stages of initiation, differentiation and development on a genome-wide scale, to find the interconnection among IAA, miRNAs and DNA methylation, and to confirm the epigenetic mechanism of initiation, differentiation and development of cotton fiber regulated by IAA, in order to enrich the regulating theory on cotton fiber differentiation and development, as well as to supply excellent foundation for creating and breeding new cotton germplasm with molecular techniques.

棉花是世界上最重要的纤维作物。棉纤维是胚珠表皮细胞经分化、发育形成的单细胞纤维，其起始分化阶段是影响棉纤维产量与品质的重要时期。IAA对棉纤维起始分化发育有重要影响，但其分子调控机理还缺乏系统研究。本项目拟以胚珠内源IAA含量差异明显的转iaaM基因棉花种质系IF11及其受体J-14为材料，基于新一代高通量测序技术small RNA-Seq和全基因组亚硫酸氢盐测序（WGBS），运用SL-RTPCR和5'-RLM-RACE等技术结合miRDeepFinder和RepeatMasker等方法从全基因组规模解析鉴定棉纤维起始与分化发育阶段miRNAs表达及DNA甲基化特征，探寻棉纤维起始与分化发育阶段“IAA—miRNAs—DNA甲基化”间的相互联系，明确IAA调控棉纤维起始与分化发育的表观遗传机理，以丰富棉纤维分化发育的调控理论，并为利用分子手段创制优异的棉花新种质提供基础。

棉纤维起始发育阶段是影响棉纤维产量与品质的重要时期。IAA对棉纤维起始发育有重要影响，但其分子调控机理还缺乏系统研究。本项目研究通过以胚珠内源生长素含量差异明显的转iaaM基因棉花种质IF11和受体材料，及通过对TM-1外施IAA，内源与外源两条途径，结合高通量测序技术（Small RNA-Seq）和全基因组亚硫酸氢盐测序（WGBS）等方法解析鉴定了棉纤维起始发育阶段MicroRNA及其DNA甲基化特征，鉴定到了一批IAA表达水平不同引起棉纤维起始发育阶段差异表达的新miRNAs，分析了差异表达的miRNA的靶基因涉及的调控网络，重点验证了ghr-miR156c、ghr-miR7504a、ghr-miR73、ghr-miR393、ghr-miR11和ghr-miR37等6个差异表达的miRNAs及与之对应的SPL9、CRE1、TIR1、PSF、MYB33、bZIP和DELLA等7个靶标基因之间的关系与在纤维起始分化中的重要功能；明确了IAA对纤维起始期棉花胚珠DNA甲基化的特征有影响，并通过影响DNA甲基化调控棉花纤维起始发育。本研究揭示了IAA影响棉纤维起始发育的转录调控机制,初步明确了IAA调控棉纤维起始发育的表观遗传机理，，并为分子手段创制优异棉花新种质提供了理论基础。