中文摘要：

苦马豆（Sphaerophysa salsula）是荒漠区重要的豆科植物。为了研究其共生根瘤菌的多样性,本试验采用16S rDNA PCR-RFLP和16S rDNA全序列分析方法,对西北部分地区的苦马豆根瘤菌进行了遗传多样性及系统发育分析。结果表明,57株供试菌株共产生了9种遗传图谱类型,对每种图谱类型的代表性菌株进行16S rDNA全序列分析的结果表明,它们分别归属于中慢生根瘤菌属（Mesorhizobium）、根瘤菌属（Rhizobium）、中华根瘤菌属（Sinorhizobium）、土壤杆菌属（Agrobacterium）、叶杆菌属（Phyllobacterium）和Shinella kummerowiae。不同地域的菌株在多样性方面也有明显差异：分离自银川的苦马豆根瘤菌的Jaccard相似性系数较低;而来自民乐县和临泽县的菌株有着非常丰富的遗传多样性,其Simpson指数分别为0.826和0.710,Shannon-Wiener指数分别为1.831和1.530。以上结果为进一步确定西北地区豆科植物根瘤菌的系统分类地位提供了依据。

英文摘要：

Sphaerophysa salsula is a highly nutritive and drought-tolerant perennial grass distributed in mid-Asia and northwestern China. This legume plant is highly prized for the revegetation of drought and high alkali soils. Our objective was to better understand the diversity and phylogeny of rhizobia collected from nodules of Sphaerophsa salsula in different regions of northwestem China. We estimated genetic diversity using 16S rDNA PCR-RFLP and 16S rDNA sequencing. Nine genotypes were tested from 57 strains. 16S rDNA sequencing revealed that these rhizobial strains belonged to the following genera： Mesorhizobium, Rhizobium, Sinorhizobium, Agrobacterium, Phyllobacterium and Shinella kummerowiae. The Jaccard simi- larity coefficient of the strains from Yinchuan was low while the strains isolated from Minle and Linze had rich diversity, with Simpson indices of 0.826 and 0.710, respectively, and Shannon-Wiener indices of 1.831 and 1.530, respectively. This study provides basic information for the phylogeny of rhizobia in northwestern China.