Recombinase A gene of rhizobium bacteria isolated from root nodules of bambara groundnuts [Vigna subterranea L. Verdc.] in Lake Victoria basin.

Recombinase A gene for rhizobium bacteria isolated form root nodules of bambara groundnuts [Vigna subterranea L. Verdc.] in Lake Victoria basin. RecA genes had uniform sizes of about 530 base pairs . The NCBI accession numbers of recA genes of isolates from this study are given (KJ736760 toKJ736764). Partial sequences of recA genes were used to construct a phylogenetic tree. Two groups A and B were obtained with Group A constituting two clades AI and AII. Clade AI had isolates BAMsp2, BAMKar1, BAMsp2 and BAMkis2 all clustered at 100% bootstrap support with Rhizobium sp. strain VIAD13G and PEPSM18. Isolate BAMKbay2 appeared to form a separate sub-clade indicating its slight genetic difference with the former isolates. Isolates BAMKbay1 and BAMKbay9 strongly clustered with Agrobacterium tumefaciens strain 11-17T B5 at 100% bootstrap support. The second sub-clade AII consisted of BAMKis1 and BAMKar2 which clustered with Rhizobium tropici (NCBI HF563598) and Rhizobium sp. strains BICC 651R and NCPPB 4062 at 99% support. This clustering trend indicated the likelihood of the two latter strains being within the species Rhizobium tropici. Group B had isolates BAMKis8 and BAMKis12 which clustered Bradyrhizobium elkanii strain C9 at 98% similarity index. An equal gene length of recA gene sequence of Pseudomonas sp. strain L1-44-08 was used as an out-group to root the phylogenetic tree.本研究涉及从维多利亚湖盆地班巴拉花生（Vigna subterranea L. Verdc.）根瘤中分离得到的根瘤菌的重组酶A基因（Recombinase A gene，后文简称recA基因）。 本研究中获得的所有recA基因长度均一，约为530个碱基对。本研究分离株的recA基因在NCBI的登录号区间为KJ736760至KJ736764。 选取recA基因的部分序列构建系统发育树。系统发育树共划分为A、B两个类群，其中类群A又包含两个亚类群AI与AII。亚类群AI包含分离株BAMsp2、BAMKar1、BAMsp2与BAMkis2，该类群与根瘤菌属未定种（Rhizobium sp.）菌株VIAD13G及PEPSM18以100%的自举支持度聚为一支。分离株BAMKbay2单独构成一个独立亚分支，表明其与前述分离株存在细微遗传差异。分离株BAMKbay1与BAMKbay9则以100%的自举支持度与根癌农杆菌（Agrobacterium tumefaciens）菌株11-17T B5聚为一支。第二个亚类群AII包含分离株BAMKis1与BAMKar2，该类群与热带根瘤菌（Rhizobium tropici，NCBI登录号HF563598）以及根瘤菌属未定种菌株BICC 651R、NCPPB 4062以99%的自举支持度聚为一支。该聚类趋势表明，后两株菌株大概率隶属于热带根瘤菌（Rhizobium tropici）物种。 类群B包含分离株BAMKis8与BAMKis12，二者以98%的相似性指数与埃尔坎慢生根瘤菌（Bradyrhizobium elkanii）菌株C9聚为一支。选取假单胞菌属未定种（Pseudomonas sp.）菌株L1-44-08的等长度recA基因序列作为外类群，为系统发育树定根。