Turner S L, Rigottier-Gois L, Power R S, Amarger N, Young J P
Department of Biology, University of York, UK.
Microbiology (Reading). 1996 Jul;142 ( Pt 7):1705-13. doi: 10.1099/13500872-142-7-1705.
Homologues of the plasmid replicator gene repC were detected and characterized in a sample of Rhizobium leguminosarum strains. Conserved PCR primers were designed from published sequences of repC; they amplified a fragment of about 750 bp from 39 out of 41 strains tested, and also from several Sinorhizobium strains, including S. meliloti. Restriction endonuclease digestion showed that the PCR product from individual strains, though uniform in size, was often heterogeneous in sequence. PCR products from 24 field isolates of R. leguminosarum from France, Germany and the UK were cloned and partially sequenced from both ends. Phylogenies constructed from the 5' and 3' ends (200 bp each) were largely congruent and demonstrated four clearly defined groups plus several unique strains. Published Agrobacterium repC sequences fall within the phylogeny of R. leguminosarum sequences, though not within any of the four groups. Specific pairs of PCR primers were designed for each of the four groups; 29 out of 41 R. leguminosarum strains gave a PCR product of the expected size with more than one group-specific primer pair. We hypothesize that the sequence groups correspond to incompatibility groups of Rhizobium plasmids.
在一批豌豆根瘤菌菌株样本中检测并鉴定了质粒复制基因repC的同源物。根据已发表的repC序列设计了保守的聚合酶链式反应（PCR）引物；这些引物从41株受试菌株中的39株，以及包括苜蓿中华根瘤菌在内的几种中华根瘤菌菌株中扩增出了一段约750 bp的片段。限制性内切酶消化显示，来自各个菌株的PCR产物，尽管大小一致，但序列往往是异质的。对来自法国、德国和英国的24株豌豆根瘤菌田间分离株的PCR产物进行了克隆，并从两端进行了部分测序。根据5'端和3'端（各200 bp）构建的系统发育树基本一致，显示出四个明确的组以及几个独特的菌株。已发表的农杆菌repC序列属于豌豆根瘤菌序列的系统发育范围，但不在四个组中的任何一组内。针对这四个组分别设计了特定的PCR引物对；41株豌豆根瘤菌菌株中有29株用不止一对组特异性引物对扩增出了预期大小的PCR产物。我们推测这些序列组对应于根瘤菌质粒的不相容组。
