一株能在大豆上结瘤的苜蓿中华根瘤菌

苜蓿中华根瘤菌(Sinorhizobium meliloti)XJ96077分离自新疆的苜蓿根瘤中，其原宿主为紫花苜蓿(Medicago sativa)。交叉结瘤试验发现，它既可在苜蓿上又能在大豆上结瘤固氮。DNA(G C)mol％分析表明，XJ96077的DNA(G C)mol％为61．9％，与已报道的根瘤菌属的DNA(G C)mol％范围(59％-64％)相符。DNA同源性分析表明，XJ96077与苜蓿中华根瘤菌USDA1002^T和042BM的同源性分别达到93％和80％，说明XJ96077归属于苜蓿中华根瘤菌。应用绿色荧光蛋白基因标记XJ96077，得到重组菌株XJ96077(G)。将其接种普通紫花苜蓿，通过激光共聚焦荧光显微镜可以检测到标记基因的表达。接种北引1号大豆上，同样可以清楚地观察到标记基因在根瘤中的表达，从而确证了XJ96077能同时在苜蓿和大豆上结瘤。通过不同品种大豆的结瘤试验，发现XJ96077对大豆品种的结瘤能力不同。

A Sinorhizoboium meliloti Strain That Can Nodulate Soybean Plants

Sinorhizobium meliloti XJ96077 was isolated from root nodules of alfalfa(Medicago sativa) in Xinjiang Region of China. Nodulation experiments showed that both soybean and alfalfa were effectively nodulated by XJ96077. The DNA (G C) mol% of strain XJ96077 was 61.9%. The DNA homologies of strain XJ96077 were 93% and 80% with S. meliloti USDA1002 T and 042BM, respectively. These results showed that XJ96077 belongs to Sinorhizobium meliloti. To prove the capability of XJ96077 to nodulate both soybean and alfalfa, constitutively expressed green fluorescence protein gene gfp was introduced to XJ96077, and the recombinant strain XJ96077(G) was obtained. Root nodules of the soybean and alfalfa inoculated with XJ96077(G) and the expression of gfp were observed using the confocal laser scanning microscope. XJ96077 showed various nodulation capacities with different soybean cultivars.