Classification of rhizobia based on nodC and nifH gene analysis reveals a close phylogenetic relationship among Phaseolus vulgaris symbionts
Classification of rhizobia based on nodC and nifH gene analysis reveals a close phylogenetic relationship among Phaseolus vulgaris symbionts
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DOI：
10.1099/00221287-147-4-981
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发表时间：
2001-04-01
期刊：
影响因子：
2.8
通讯作者：
Amarger, N
中科院分区：
文献类型：
--
作者：
Laguerre, G;Nour, SM;Amarger, N
在83株根瘤菌中鉴定了nifC和nifH基因，这些根瘤菌代表了分布在根瘤菌属、中华根瘤菌属、中慢生根瘤菌属和慢生根瘤菌属中的23个公认的物种，以及来自各种宿主豆科植物的未分类的根瘤菌。保守引物设计从现有的核苷酸序列，并能够扩增约930 bp和780 bp的nifH片段，分别从大多数菌株的调查。PCR产物的RFLP分析导致这些根瘤菌的分类，这是在一般良好的相关性，其已知的主机范围和独立的分类地位。对不同属种的代表菌株进行了nifH和nifC片段的测序，其中大部分来源于菜豆根瘤。系统发育树的构建和揭示了密切的共生基因的菜豆共生体，无论其16 S-rDNA为基础的分类。NifC和nifH基因的同源性基本相似，但也发现了不一致的情况，这表明在进化过程中发生了基因重排。这些结果支持这样的观点，即横向遗传转移根瘤菌物种，在某些情况下，在根瘤菌和中华根瘤菌属起着多样化和结构的自然种群的根瘤菌。
The nodC and nifH genes were characterized in a collection of 83 rhizobial strains which represented 23 recognized species distributed in the genera Rhizobium, Sinorhizobium, Mesorhizobium and Bradyrhizobium, as well as unclassified rhizobia from various host legumes. Conserved primers were designed from available nucleotide sequences and were able to amplify nodC and nifH fragments of about 930 bp and 780 bp, respectively, from most of the strains investigated. RFLP analysis of the PCR products resulted in a classification of these rhizobia which was in general well-correlated with their known host range and independent of their taxonomic status. The nodC and nifH fragments were sequenced for representative strains belonging to different genera and species, most of which originated from Phaseolus vulgaris nodules. Phylogenetic trees were constructed and revealed close relationships among symbiotic genes of the Phaseolus symbionts, irrespective of their 16S-rDNA-based classification. The nodC and nifH phylogenies were generally similar, but cases of incongruence were detected, suggesting that genetic rearrangements have occurred in the course of evolution. The results support the view that lateral genetic transfer across rhizobial species and, in some instances, across Rhizobium and Sinorhizobium genera plays a role in diversification and in structuring the natural populations of rhizobia.