Wheatcroft R, Watson R J
Plant Research Centre, Agriculture Canada, Ottawa, Ontario.
J Gen Microbiol. 1988 Jan;134(1):113-21. doi: 10.1099/00221287-134-1-113.
An internal 0.9 kb segment of Rhizobium meliloti insertion sequence ISRm1 was used as a probe to determine the distribution of ISRm1 in strains of R. meliloti and other Gram-negative bacteria. The insertion sequence was detected in 80% (12/15) of R. meliloti strains from different parts of the world. Its copy number ranged from one to at least eleven. The ISRm1 copies detected showed variation in their internal restriction sites and their degree of homology to the probe. ISRm1 was found in a variety of genomic restriction fragments, and was detected in plasmids, including the nod and exo megaplasmids of R. meliloti. Other rhizobia found to contain ISRm1 were a strain of R. leguminosarum biovar phaseoli and two Rhizobium isolates capable of nodulating both Medicago sativa and Phaseolus vulgaris. It was also found in a diazotrophic soil bacterium isolated from the roots of wetland rice.
用苜蓿根瘤菌插入序列ISRm1的一段0.9 kb内部片段作为探针，来确定ISRm1在苜蓿根瘤菌菌株及其他革兰氏阴性菌中的分布情况。在来自世界各地的80%（12/15）苜蓿根瘤菌菌株中检测到了该插入序列。其拷贝数从1到至少11不等。检测到的ISRm1拷贝在其内部限制酶切位点以及与探针的同源程度上存在差异。ISRm1存在于多种基因组限制片段中，并且在质粒中也被检测到，包括苜蓿根瘤菌的结瘤和外生多糖大质粒。发现含有ISRm1的其他根瘤菌有一株菜豆根瘤菌生物变种菜豆以及两株能够使紫花苜蓿和菜豆结瘤的根瘤菌分离株。在从湿地水稻根部分离出的一种固氮土壤细菌中也发现了它。
