海岛棉心皮结构分化特征及其转录组的比较研究

“Out of floc” in sea-island cotton plant is an urgent difficult problem to be solved in cotton production，due to its boll lack effective sustain which is formed by 3 carpel, as while the boll of upland cotton form 4-5 carpels.And the boll’s structure comes from the carpel enclosed to form the ventricle, so it is a passive road for solving this problem by handing with the carpel. In this study, the carpel development features in three different types of sea-island cotton will be observed to determine the dynamic formation process.The microstructure of flower bud and carpel in sea-island cotton will be compared with that of upland cotton, and the formation period and microstructure of carpel will be explored clearly to determine the pattern of development of carpel in sea-island cotton; On the other hand, the transcriptome information during the differentiation of carpel from flower bud will be obtained by means of RNA-Seq technology, the type of carpel-related genes in sea-island also will be analyzed, and the enrichment level of each gene and possible existent gene interactions will be explained deeply. At the same time, by homologous cloning strategy, two genes with specific expressing and high abundance in carpel will be cloned to further excavate of the function of this gene in carpel formation. This is the first attempt to explore the formation mechanism of differentiation from flower bud to carpel in sea-island cotton and the regulatory function of associated gene.The findings may reveal further the development process of carpel formation. It will provide comprehensive analysis of the cause for the“out of floc” and lay foundation for directional selection of the sea-island cotton varieties without“out of floc”.

“掉絮”是新疆海岛棉生产中亟待解决的难题，主要因为它以3瓣为主，与4-5瓣陆地棉相比棉瓣缺乏有效支撑；心皮围合的心室将来发展为可支撑的铃壳结构。因此，从心皮入手揭示掉絮成因是一条可行之路。本研究拟通过观察三种不同心皮棉花的心皮发育特征，探明海岛棉花芽分化至心皮形成的动态过程，并与陆地棉的花芽心皮的显微结构进行对比，具体定位清楚心皮形成时期及其微观结构，探究海岛棉心皮发育的规律；另一方面，借助RNA-Seq技术研究心皮形成过程中的转录组信息，分析海岛棉心皮相关的基因种类，并深入阐释各基因的丰度水平及可能存在的基因互作关系。同时，通过同源克隆策略，克隆两个在心皮中特异表达的相关基因，进一步深入挖掘该基因在心皮形成中的功能。该研究首次尝试探索海岛棉花芽分化心皮的形成机制及其相关的基因调控功能，研究结果可深入揭示海岛棉心皮发育形成机制，为全面解析海岛棉掉絮的成因，定向选育不掉絮的海岛棉品种奠定基础

棉花心皮最终发育成雌蕊器官，对于产量性状的形成极为重要，由于心皮发育早期非常隐蔽难以取样，导致其研究进展缓慢。本项目以3、4、5心皮棉花品种为研究材料，以心皮发育特征和控制心皮发育的基因为研究内容，以花芽分化期为心皮研究的关键节点，采用田间多点、室内鉴定等鉴定手段，结合电镜技术、RNA-seq、QRT-PCR和同源克隆与转化技术，围绕海岛棉心皮表型、生理生化、基因功能等进行心皮发育多维度解析。研究认为心皮发育可分为6个阶段，现蕾后3d心皮分化期是心皮数量形成的关键时期，5-6d心皮的形态基本完成；25d左右心皮柱头到达花柱顶端，35d左右花发育完成；开花后22-24d心皮不再增大，48-50d心皮逐渐脱水。3心皮品种在花芽分化初始期IAA、JA含量低于4、5皮品种。同时，研究获得了控制海岛棉心皮形成的基因及种类，筛选出植物激素、细胞能量代谢，脂肪酸代谢，次生代谢等信号途径17个可能与心皮发育相关的候选基因，其中FIE，CLV3，AG，DR5，AR，SPT，FIL 共7个差异基因在不同组织中表达量较高。进一步通过采用同源克隆技术构建表达载体，进行转化拟南芥，验证了7个基因对海岛棉心皮发育均起重要的作用。.综上所述，本项目较好完成了项目研究内容，研究工作为后期定向培育多心皮的新品种、提高棉花产量水平提供了重要的理论依据和技术参考。