Deduction of minimum sysmbiosis island gene sets for Lotus rhizobia

为了推测荷花中根瘤菌与荷花共生的最小共生基因集，我们比较了3株荷花中根瘤菌共生岛的核苷酸序列，发现155个基因在它们之间完全保守。我们制备了可控制的启动子和新的可选择标记，用于洛氏支原体菌株。我们还通过诱变pBBR1MCS2的代表基因，制备了一种对温度敏感的广宿主载体衍生物。此外，我们对多个洛蒂分枝杆菌菌株进行了Next Generation Sequencing分析，并将获得的reads定位到菌株MAFF303099的基因组序列上。研究结果支持了罗氏分枝杆菌主要染色体存在分化的观点，表明其共生岛核心结构较为保守。

In an attempt to deduce the rhizobial minimum symbiosis gene sets for mutualism between Mesorhizobium loti and Lotus species, we compared nucleotide sequences of symbiosis islands of three M. loti strains and found 155 genes are completely conserved among them. We made controllable promoters and new selectable markers to be used with M. loti strains. We also made a temperature sensitive derivative of the broad-host range vector pBBR1MCS2, by mutagenesis of its rep gene. In addition, we performed Next Generation Sequencing analysis of several M. loti strains and mapped the obtained reads on the genome sequence of the strain MAFF303099. The results supported the divergence of main chromosomes among M. loti strains with conserved core structure of symbiosis island.