Departamento de Biología Molecular, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba, Argentina.
J Basic Microbiol. 2010 Jun;50(3):274-9. doi: 10.1002/jobm.200900245.
RSalpha sequencing is a valuable tool for identification of bacterial strains, and for evaluating the genetic structure of indigenous rhizobial populations. The purpose of this study was to evaluate, qualitatively, the presence or absence of RSalpha fragment in peanut-nodulating strains isolated from plants grown at four sites in central Argentina. RSalpha fragment was found in only three of 26 indigenous strains, and in one of three inoculant strains analyzed. In contrast to results from studies of other symbiotic nitrogen-fixing bacteria, such as soybean-nodulating strains, no correlation was found between generation time and presence of RSalpha sequence. Phylogenetic analysis of the 16S rRNA gene sequence grouped peanut-nodulating strains into two clusters, Bradyrhizobium japonicum vs. B. elkanii, and showed divergence among strains positive for RSalpha sequence. Our results confirm the genetic diversity previously reported for various peanut-nodulating rhizobial strains, and indicate that the RSalpha fragment is not applicable as a marker or tool for competition assays at the field or ecological level.
RSalpha 测序是鉴定细菌菌株和评估土著根瘤菌种群遗传结构的有效工具。本研究的目的是定性评估在阿根廷中部四个地点生长的植物中分离出的花生结瘤菌株中 RSalpha 片段的存在或缺失情况。在 26 个土著菌株中仅发现了三个，在分析的三个接种剂菌株中发现了一个。与对其他共生固氮细菌（如大豆结瘤菌株）的研究结果相反，未发现世代时间与 RSalpha 序列存在之间存在相关性。16S rRNA 基因序列的系统发育分析将花生结瘤菌株分为两个聚类，即日本根瘤菌与 B. elkanii，并且在 RSalpha 序列阳性的菌株之间存在分化。我们的结果证实了先前报道的各种花生结瘤根瘤菌株的遗传多样性，并表明 RSalpha 片段不适用于田间或生态水平的竞争测定的标记或工具。
