マメ科樹木由来の根粒形成細菌の多様性とその動態

研究了26株来源于印度尼西亚豆科植物镰叶拟除虫菊（Paraserianthes falcataria）的根瘤菌的表型、性状、共生特性和遗传变异。根据它们的共生模式以及其他表型特征，我们发现这些根瘤菌群之间存在着广泛的变异。随机选择的菌株的16S rDNA基因的近全长序列显示，菌株可以分为三个主要群体。第1组与热带根瘤菌（Rhizobium tropicii）亲缘关系较近，第2组与埃氏慢生根瘤菌（Bradyrhizobium elkanii）亲缘关系较近，第3组与日本慢生根瘤菌（Bradyrhizobium japonicum）和芽生根瘤菌（Blasthizobium ficans）亲缘关系较近。本研究还表明，豆科树种南洋豆（Paraserianthes falcataria）能与快生型和慢生型根瘤菌建立共生关系并形成根瘤，至少能与3种根瘤菌建立共生关系。从结核中分离出21株细菌菌株，并进行16S rDNA测序分析。鉴定出一新属和若干新种。表明从冲绳豆科植物根瘤中分离的细菌具有广泛的分化，可能存在定位和宿主特异性。

Twenty six rhizobial isolates nodulated Indonesian tree legume, Paraserianthes falcataria, were studied for phenotype.characters, symbiotic properties and genetic variation. On the basis of their symbiotic pattern as well as other phenotype characters, we found that there is a wide variation within those rhizobia group. Nearly full-length sequences of 16S rDNA genes of randomly selected isolates showed that the isolates could be divided into three main groups. Group1, which have a closely relationship with reference strains Rhizobium tropicii, group 2 contains isolates which high similarity with reference strain Bradyrhizobium elkanii, and the rest (group 3) were closely related to reference strains Bradyrhizobium japonicum and Blastobacter denitrificans. This present finding also demonstrated that the leguminous tree Paraserianthes falcataria could establish symbiotic relationship and form nodules with both fast growing as well as slow growing rhizobia, and at least with three species of rhizobia.To study for the diversity of the nodule forming bacteria we collected the nodule from 25 kinds of regume in Okinawa. Twenty first bacterial strains were isolates and from the nodules and performed to analysis of 16S rDNA sequencing. One new genus and some new species were determined. It was suggested that the bacteria isolated from nodules of leguminous plants in Okinawa have widely diverged and there is maybe localization and host specificity.