玫瑰色考克氏菌SDB9高水平合成生长素的分子机理研究

生长素（auxin）的天然形式吲哚乙酸（IAA）在植物的生长发育过程中发挥重要作用，而且越来越多的证据表明生长素在植物与微生物相互作用过程中发挥重要作用。植物和微生物体内的IAA有多条合成途径，但每条途径中具体的生物反应机制尚有许多研究空白，不同种类的生物个体所依赖的主要合成途径也有待明确。对于革兰氏阳性菌合成IAA的途径了解更少。本研究前期从沙地柏根部分离到具有显著促进植物生长作用的PGPR细菌SDB9，该菌属于玫瑰色考克氏菌属，革兰氏阳性，能高水平合成IAA，全基因组分析存在该菌可能同时存在色氨酸依赖和非依赖的IAA合成途径，本项目拟采用饲喂试验并结合代谢组学分析及同位素标记分析、原核转录组分析确定SDB9菌体内存在的IAA合成途径及关键基因，并通过遗传试验（基因敲除、互补、表达）和生化试验（确定相关酶的活性）来验证相关基因的功能，最终揭示SDB9菌高水平合成IAA的分子机理。

IAA, the natural form of auxin, plays an important role in plant growth and development, and more and more evidences show that auxin plays an important role in plant microbial interaction. There are many synthetic pathways of IAA in plants and microorganisms, but there are many gaps in the specific biological reaction mechanism of each pathway, and the main synthetic pathways that different kinds of biological individuals depend on are still to be clarified. Less is known about the synthesis of IAA by Gram-positive bacteria. In the early stage of this study, the PGPR bacteria SDB9 was isolated from the roots of Sabina vulgaris, which had a significant effect on plant growth. The bacteria belonged to Kocuria. It was Gram-positive and could synthesize IAA at a high level. The whole genome analysis shows that the bacteria may have tryptophan dependent and independent IAA synthesis pathway at the same time. In this project, feeding experiment, metabolomic analysis, isotope labeling analysis and prokaryotic transcriptome analysis are used to determine the IAA synthesis pathway and key genes in SDB9 bacteria, and genetic experiment (knockout, complementation, expression) and biochemical experiment (prokaryotic expression that to determine the activity of related enzymes) to verify the function of related genes, and finally decipher the molecular mechanism of high level synthesis of IAA by SDB9.