亚洲棉有限生长突变体基因Gadt1的克隆与功能分析

To get better production, pruning and growth inhibitors are essential managements for controlling the indeterminate growth habit in cotton planting. These treatments not only increased the costs but also restricted the improvement of cotton industry in our country. By ethyl methane sulphonate (EMS) mutagenesis, a determinate growth mutant (Gadt1) was induced from Gossypium arboreum L. for the first time. The stem apex of mutant was terminated by a flower after emerging 7-8 branches. With the determinate growth habit, no pruning operation is needed any more. Genetic analysis showed that dt1 was caused by a single recessive allele mutation. Furthermore, we have performed transcriptome analyses of dt1 and WT (Shixiya1) plants during the square forming period. By BSA-seq analysis, Gadt1 gene was mapped on Chr12 between 18.74 Mb and 22.08 Mb. A total of 323 differentially expressed genes were identified, of which flowering transition related genes were highly enriched. In this project, an enlarged mapping population will be used to finely map and clone the Gadt1 gene based on the above researches. And, DT1 gene overexpressed and genome-editing transgenic mutants would be obtained in upland cotton. Finally, combining with previous transcriptome data, we could elucidate the molecular regulatory network of determinate growth in cotton. After this study, we will provide the useful gene and germplasm resources for cotton breeding.

为了提高产量，控制棉花无限生长的习性，整枝、打顶以及化控等在生产中广泛应用，不仅增加了成本，也限制着我国棉花产业的发展。项目组前期利用EMS诱变技术，获得了一个亚洲棉有限生长突变体（determinate growth 1，dt1），其主茎生长点分化形成7-8个果节后，以开花终结，无需人工打顶、化控等操作。遗传分析表明，dt1为单基因隐性突变；通过BSA-seq方法，Gadt1基因初定位于Chr12的18.74 Mb-22.08 Mb区间内；利用转录组测序分析鉴定到323个差异表达的基因，其中开花途径相关基因显著富集。本项目拟在上述研究的基础上，通过构建大群体，精细定位、克隆Gadt1基因，通过转基因在陆地棉中获得过表达材料和基因编辑突变体，结合转录组数据分析DT1基因参与的调控网络，阐明棉花有限生长的分子机制，为棉花株型育种提供有效基因和种质资源。

生长习性是一种重要的农艺性状，对作物的结构和产量起着决定性的作用。棉花的无限生长习性，不适合机械化生产。本研究通过EMS诱变，在亚洲棉中鉴定到一个有限生长突变体（dt1），该突变体主轴茎尖分生组织转变为终端花结束无限生长。基于dt1位点的基因图位克隆显示，在TERMINAL FLOWER 1 (GaTFL1)的201个位点发生了一个由G到A的单核苷酸突变，改变了5'端RNA 剪接位点，导致GaTFL1蛋白31个氨基酸缺失和功能丧失。RNA-Seq分析发现了许多负责植物激素、次生代谢产物(如生长素、糖和类黄酮)的转运蛋白，这些转运蛋白可能在GaTFL1下游发挥作用，进而参与植物结构调节。这些发现揭示了一种新的剪接机制参与了转录后修饰，并表明TFL1可能在生长素和糖通路上游发挥作用，通过介导它们的转运来决定茎尖分生组织(SAM)的命运，并协调植物的营养和生殖发育。总体而言，本研究为TFL1在植物发育调控中的作用机制提供了线索，同时也为植物结构改良提供了研究策略。