Bamba Masaru, Nakata Sayuri, Aoki Seishiro, Takayama Koji, Núñez-Farfán Juan, Ito Motomi, Miya Masaki, Kajita Tadashi
Department of Biology, Graduate School of Science, Chiba University, 1-33 Yayoi, Inage, Chiba-shi, Chiba, 263-8522, Japan.
Jumonji Junior and Senior High School, 1-10-33 Kitaohtsuka, Toshima-ku, Tokyo, Japan.
Antonie Van Leeuwenhoek. 2016 Dec;109(12):1605-1614. doi: 10.1007/s10482-016-0761-y. Epub 2016 Sep 23.
To understand the geographic distributions of rhizobia that associated with widely distributed wild legumes, 66 nodules obtained from 41 individuals including three sea-dispersed legumes (Vigna marina, Vigna luteola, and Canavalia rosea) distributed across the tropical and subtropical coastal regions of the world were studied. Partial sequences of 16S rRNA and nodC genes extracted from the nodules showed that only Bradyrhizobium and Sinorhizobium were associated with the pantropical legumes, and some of the symbiont strains were widely distributed over the Pacific. Horizontal gene transfer of nodulation genes were observed within the Bradyrhizobium and Sinorhizobium lineages. BLAST searches in GenBank also identified records of these strains from various legumes across the world, including crop species. However, one of the rhizobial strains was not found in GenBank, which implies the strain may have adapted to the littoral environment. Our results suggested that some rhizobia, which associate with the widespread sea-dispersed legume, distribute across a broad geographic range. By establishing symbiotic relationships with widely distributed rhizobia, the pantropical legumes may also be able to extend their range much further than other legume species.
为了解与广泛分布的野生豆科植物相关的根瘤菌的地理分布情况，我们研究了从41个个体中获取的66个根瘤，这些个体包括三种通过海洋传播的豆科植物（滨海豇豆、黄毛豇豆和玫瑰刀豆），它们分布在世界热带和亚热带沿海地区。从根瘤中提取的16S rRNA和nodC基因的部分序列显示，只有慢生根瘤菌属和中华根瘤菌属与泛热带豆科植物相关，并且一些共生菌株在太平洋广泛分布。在慢生根瘤菌属和中华根瘤菌属谱系中观察到了结瘤基因的水平基因转移。在GenBank中进行的BLAST搜索还鉴定出了来自世界各地各种豆科植物（包括作物品种）的这些菌株的记录。然而，其中一种根瘤菌菌株在GenBank中未被发现，这意味着该菌株可能已经适应了滨海环境。我们的结果表明，一些与广泛传播的通过海洋传播的豆科植物相关的根瘤菌分布在广泛的地理范围内。通过与广泛分布的根瘤菌建立共生关系，泛热带豆科植物也可能比其他豆科物种能够进一步扩大其分布范围。
