海南快生根瘤菌I66的部分16S rRNA序列测定

与豆科植物共生固氮的根瘤菌目前有4个属、10个种.包括Rhizobium(6个种),Sinorhizobium(2个种),Azorhizobium(1个种)和Bradyrhizobium(1个种).其中多数是近年来采用现代分类技术分析后建立的,而且新的类群还在不断被发现.在以前的根瘤菌数值分类及DNA-DNA杂交研究中,我们确定了海南慢生型根瘤菌属于大豆慢生根瘤菌种(B.japonicum).而海南快生型根瘤菌的分类地位则较为分散.其中一些菌株属于已知各根瘤菌种,另有4株银合欢根瘤菌和13株来自不同寄主的菌株分别构成具有独立的分类地位的两个菌群(第2群和第4群)(待发表).为了进一步明确它们的分类地位,我们依据国际系统细菌学委员会根瘤菌分委员会的建议,利用Young等建立的聚合酶链反应(PCR)及测序技术,对第4群的代表菌株166的部分16SrRNA基因片段进行了扩增和测序.

PHYLOGENY OF A FAST-GROWING RHIZOBIAL GROUP ISOLATED FROM HAINAN PROVINCE

Based on the former researches of numerical taxonomy and DNA-DNA hybridization, a distinct group of fast-growing rhizobia was constructed including 13 strains isolated from a various range of leguminous plants from Hainan Province. This paper reported the partial 16S rRNA sequencing of the representative strain,166,of this rhizobial group by polymerase chain reaction (PCR) and cloning in phage M13. The sequence obtained from this research was compared with those of relative bacteria that have been publised. The distance was calculated and a phylogenetic tree was drawn based on the sequence data. The differences in the compared fragment were 7,8,25,35 and 26 bases between I66 and R. leguminosarum, R. meliloti, Agrobacterium tumefaciens, Azarhizobium caulinodans, and Bradyrhizobium japonicum , respectively. These results indicated that the Hainan group represented by I66 was a new species of Rhizobium.