Lafay B, Burdon JJ
Centre for Plant Biodiversity Research, CSIRO Plant Industry, Canberra ACT 2601, Australia.
Appl Environ Microbiol. 1998 Oct;64(10):3989-97. doi: 10.1128/AEM.64.10.3989-3997.1998.
The structure of rhizobial communities nodulating native shrubby legumes in open eucalypt forest of southeastern Australia was investigated by a molecular approach. Twenty-one genomic species were characterized by small-subunit ribosomal DNA PCR-restriction fragment length polymorphism and phylogenetic analyses, among 745 rhizobial strains isolated from nodules sampled on 32 different legume host species at 12 sites. Among these rhizobial genomic species, 16 belonged to the Bradyrhizobium subgroup, 2 to the Rhizobium leguminosarum subgroup, and 3 to the Mesorhizobium subgroup. Only one genomic species corresponded to a known species (Rhizobium tropici). The distribution of the various genomic species was highly unbalanced among the 745 isolates, legume hosts, and sites. Bradyrhizobium species were by far the most abundant, and Rhizobium tropici dominated among the Rhizobium and Mesorhizobium isolates in the generally acid soils where nodules were collected. Although a statistically significant association occurred between the eight most common genomic species and the 32 hosts, there was sufficient overlap in distributions that no clear specificity between rhizobial genomic species and legume taxa was observed. However, for three legume species, some preference for particular genomic species was suggested. Similarly, no geographical partitioning was found.
采用分子方法对澳大利亚东南部开阔桉树林中结瘤本地灌木豆科植物的根瘤菌群落结构进行了研究。从12个地点的32种不同豆科宿主植物的根瘤中分离出745株根瘤菌菌株，通过小亚基核糖体DNA PCR-限制性片段长度多态性分析和系统发育分析，鉴定出21个基因组种。在这些根瘤菌基因组种中，16个属于慢生根瘤菌亚群，2个属于豌豆根瘤菌亚群，3个属于中生根瘤菌亚群。只有一个基因组种与已知种（热带根瘤菌）相对应。在745个分离株、豆科宿主植物和地点中，各种基因组种的分布极不均衡。慢生根瘤菌种类最多，在采集根瘤的一般酸性土壤中，热带根瘤菌在根瘤菌和中生根瘤菌分离株中占主导地位。虽然8个最常见的基因组种与32种宿主之间存在统计学上的显著关联，但分布上有足够的重叠，未观察到根瘤菌基因组种与豆科分类群之间有明显的特异性。然而，对于三种豆科植物，显示出对特定基因组种有一定偏好。同样，未发现地理分区现象。
