广金钱草根瘤菌抗逆性和遗传多样性分析

Resistance to Stresses and Genetic Diversity of Rhizobia Nodulated with Desmodium Styracifolium

分析了14株广金钱草根瘤菌对不同盐度、温度、酸碱度和重金属耐受性,并采用BOX-PCR指纹图谱和recA基因序列分析技术分析其遗传多样性.结果表明,供试菌株对不同盐度和酸碱度表现出相似的耐受性;对不同温度和不同种类的重金属则表现出不同的耐受性,其中4株供试菌株能够耐受4℃的低温.几乎所有供试的广金钱草根瘤菌都能够在含有4 mmol/L的Zn2+、Pb2+和含锌、铅双盐的YMA平板上生长,而仅有2株供试菌株能够在添加4 mmol/L Cu2+的YMA平板上生长.BOX-PCR指纹图谱分析表明,与广金钱草共生的根瘤菌在基因组水平上与已知的埃氏慢生根瘤菌相似,代表菌株的recA基因序列的系统发育分析与BOX-PCR聚类结果基本一致,供试的广金钱草根瘤菌除1株位于根瘤菌属外,其余根瘤菌均为慢生根瘤菌属.

In order to better know the biologic traits of rhizobia symbiotic with Desmodium styacifolium that is a kind of Chinese traditional medicine, we analyzed the resistance to stresses of 14 rhizobia nodulated with Desmodium sty- acifolium, including different concentrations of NaC1, temperatures, pH and heavy metals. The genetic diversity by using BOX - PCR finger printings and the phylogeny of recA gene was also performed. The results showed that the tested strains had the similar resistance to different concentrations of NaC1 and pH, but different for temperatures and heavy metals. Four rhizobial isolates can grow in the condition of 4 ℃ and most tested strains can grow on YMA plate contained 4 mmol/L Zn26 ,pb2and Zn2＋/Pb2. And two strains can resist to 4 mmol/L Cu26. The rhizo- bial isolates had the identical genomic finger printings based on BOX - PCR analysis. The representative rhizobial strains based on the phylogeny of recA gene had a similar result with BOX - PCR finger printings. One isolate be- longs to the genus of Rhizobium and other thirteen strains belong to the genus of Bradyrhizobium.