根瘤菌 z-bo 2020-11-02 346

　　Rhizobium is a type of gram-negative bacteria widely distributed in the soil. It can form a highly transformed symbiotic relationship with legumes, infect the roots of legumes, form nodules, and then fix molecular nitrogen in the air to form a Organic nitrogen used by plants; Rhizobium obtains required photosynthetic products from host plants. The study of rhizobia-legume symbiotic nitrogen fixation system and mechanism is of great significance to the sustainable development of agriculture. In recent years, thanks to high-throughput DNA sequencing, researchers have published more complete genomes of rhizobia, but the work of analyzing and verifying the functions of key genes is still insufficient.

　　The research uses Mariner transposon insertion sequencing technology (INSeq) to analyze the continuous lifestyle stages of rhizobia-legume symbiosis, and for the first time it is clear that rhizobia grow in the rhizosphere, colonize the root system, infect root hair cells, and form nodules , Differentiate into nitrogen-fixing bacteria and release essential genes at various stages from root nodules. Although only 27 genes were annotated as nitrogen fixation genes (nif and fix), the researchers found that 603 gene regions are essential genes in the process of pea nodulation and nitrogen fixation. Among them, 146 genes are essential genes for rhizosphere growth to the stage of bacteroid development. These genes highlight the importance of competition in the rhizosphere environment for later infection and nodulation; 211 genes are nodulation and bacteroid stages The specific genes of, mainly for bacterial movement, cell membrane reorganization, nodulation signal transduction, nitrogen fixation and metabolic adaptation (including urea, erythritol and aldehyde metabolism, glycogen synthesis, diacid metabolism and glutamine GlnII synthesis), etc. Function related genes. The research emphasizes the importance of multi-stage competition in symbiosis between rhizobia and host legumes, which is conducive to in-depth understanding of the interaction mechanism between the two.

　　Related research results were published on PNAS with the title Lifestyle adaptations of Rhizobium from rhizosphere to symbiosis. The team of Professor Philip Poole of the Department of Botany of Oxford University, the Key Laboratory of Plant Germplasm Innovation and Characteristic Agriculture of Wuhan Botanical Garden of Chinese Academy of Sciences, and Wuhan Botanical Garden are the co-authors of the thesis, and Li Li, associate researcher of the Kiwi Germplasm Resources and Breeding Discipline Group of Wuhan Botanical Garden First author. The research work is supported by the National Scholarship Fund Project.