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根瘤菌TtsI突变对大豆根瘤菌固氮酶活性的影响及转录组分析

Effects of TtsI Mutations in Rhizobia on the Nitrogenase Activity in Nodules and Its Transcriptome Analysis

  • 摘要: 根瘤菌与大豆建立的共生模式为大豆提供了生长发育所必须的氮素,在共生建立时根瘤菌Ⅲ型效应因子是影响结瘤发生的重要信号分子之一。为了解析根瘤菌Ⅲ型效应因子在结瘤中的作用,进行TtsI突变根瘤菌HH103(Sinorhizobium fredii HH103)结瘤鉴定以及根瘤转录组分析,并对差异基因进行富集分析。结果显示:TtsI突变可以降低绥农14根瘤的固氮酶活性,但不影响野生豆ZYD00006的根瘤固氮酶活性。TtsI突变根瘤菌HH103(HH103ΩTtsI)使绥农14根瘤内部分编码氮转运的相关基因以及NLP7下调表达,并且接种HH103ΩTtsI与接种HH103相比,Glyma.11G235200和NLP7在ZYD00006的根瘤中的相对表达没有显著差异。通过GO富集、KEGG富集以及GSEA富集分析显示,差异基因主要涉及信号传导以及代谢进程等,差异基因主要在植物激素信号传导以及MAPK信号通路上富集。研究结果为后续Ⅲ型效应因子的功能和机制的解析以及大豆高效固氮设计提供了新的思路;同时氮转运相关基因的表达差异可为进一步选育高结瘤、高固氮效率以及高氮利用率的大豆品种提供理论支撑。

     

    Abstract: The symbiotic model established between rhizobia and soybeans provides the necessary nitrogen for soybean growth and development. In the establishment of symbiosis, type Ⅲ effector factors of rhizobia is one of the important signaling molecules that affect nodulation. In order to elucidate the role of type Ⅲ effector factors of rhizobia in nodulation, this study identified TtsI mutants for nodulation and conducted transcriptome analysis of nodules, as well as enrichment analysis of differentially expressed genes. The results showed that the TtsI mutation(HH103ΩTtsI) could reduce the nitrogenase activity of Suinong 14 nodules, but did not affect the nitrogenase activity of wild soybean ZYD00006 nodules. And after the HH103ΩTtsI, some of the Suinong 14 nodules encoded nitrogen transport related genes and NLP7 were down regulated. Moreover, compared with the inoculation of HH103, there was no significant difference in the relative expression of Glyma.11G235200 and NLP7 in the ZYD00006 nodules. Finally, GO enrichment, KEGG enrichment, and GSEA enrichment analysis showed that differential genes mainly involve signal transduction and metabolic processes. The differential genes were mainly enriched in plant hormone signaling and MAPK signaling pathway. This study provides new ideas for the analysis of the functions and mechanisms of subsequent Type Ⅲ effector factors, as well as the design of efficient nitrogen fixation in soybeans. At the same time, based on the expression differences of nitrogen transport related genes, theoretical support can be provided for further breeding of soybean varieties with high nodulation, high nitrogen fixation efficiency, and high nitrogen utilization efficiency.

     

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