Abstract: Little information was available about Trifolium rhizobia from the northwestern China.In order to investigate the genetic diversity of Trifolium rhizobia in Xinjiang Uygur Autonomous Region and Shaanxi province,fifty rhizobial strains isolated from Trifolium spp.were characterized based on 16S rDNA PCR-RFLP and sequencing analysis.Five genetic patterns of 16S rDNA were obtained and they belonged to Rhizobium,Agrobacterium,and Phyllobacterium through sequencing analysis of 16S rDNA,which revealed that Trifolium rhizobia had a higher diversity.In the phylogenetic tree of 16S rDNA,CCNWXJ0140 was closely related to genus Phyllobacterium and shared 98.9% sequence homology with Phyllobacterium trifolii PETP02.Comparing with previous studies,it had extended rhizobial species associated with Trifolium spp.Further analysis show these rhizobia didn’t have geographical specificity even if they were isolated from same host plant.Therefore,our study of Trifolium spp.symbionts is of value to rhizobial resource enrichment and application in agriculture.

Key words: Trifolium L., Rhizobia, Genetic diversity, Phyllobacterium, 16S rDNA

摘要： 为阐明西北部分地区三叶草属(Trifolium L.)根瘤菌遗传多样性及系统发育地位,于2007年12月采用16S rDNA PCR-RFLP与16S rDNA全序列分析,对50株分离自新疆和陕西地区的三叶草属根瘤菌进行系统研究。结果表明:所有供试菌株产生了5种16S rDNA基因型,归属于根瘤菌属(Rhizobium)、土壤杆菌属(Agrobacterium)、叶杆菌属(Phyllobacterium)3个系统发育分支,表现出较为丰富的共生固氮体系多态性。其中,CCNWXJ0140在系统发育树中与三叶草叶杆菌模式菌株P.trifolii PETP02关系较近,序列相似性为98.9%,也扩大了可与三叶草形成共生关系的根瘤菌种类的范围。通过不同地区同一寄主的三叶草根瘤菌的比较,发现其共生关系因地理分布不同而具有多样性,因此,对于丰富三叶草根瘤菌资源及其开发利用具有重要意义。

关键词: 三叶草, 根瘤菌, 遗传多样性, 叶杆菌, 16SrDNA