快生型大豆根瘤菌(Rhizobium fredii)内源质粒在培养及共生过程中的稳定性  

STABILITY OF INDIGENOUS PLASMIDS IN RHIZOBIUM FREDII STRAINS DURING CULTURE AND SYMBIOSIS

作　　者：陈雯莉[1] 李阜棣[1] 周俊初[1] 

机构地区：[1]华中农业大学微生物系,武汉430070

出　　处：《应用与环境生物学报》1997年第1期55-62,共8页Chinese Journal of Applied and Environmental Biology

基　　金：国家自然科学基金;欧洲共同体资助

摘　　要：以湖北洪湖公离的快生型大豆根瘤菌为材料，考察了它们的内源质粒在培养过程及共生过程中的稳定性．结果表明，所有供试菌株的质粒在培养条件下比较稳定，传代50次后没有明显变异．对其中2个菌株与4种不同的大豆宿主共生过程中质粒的稳定性研究，发现HA12－1－12的共生质粒和隐性质粒高度构定，HA7－2－2的质粒却发生了不同程度的变异．质粒检测的结果及RFLP分析表明，HA7－2－2共生质粒的稳定性高于隐性质粒，而且共生质粒上携带的nodDABC和nifHDK基因相当保守，不易受宿主的影响而产生变异．盆栽试验的结果也说明，虽然HA7－2－2的内源质粒在共生过程中发生了遗传重排，但它的共生性状没有明显的变异．The stability of indigenous plasmids was investigated in 11 Rhizobium fredii strains isolated from the soil of Honghu County, Hubei Province. When these strains were transferred on culture media for 50 times, their indigenous plasmids remained highly stable. Two strains, HA12-1-12 and HA7-2-2 were tested for the stabi lity of plasmids during symbiosis with three soybean(Glycine max) cultivars(Aijiaozao, Kennong-4 and Gang 8168-4)and one wild soybean(Glycine soja). Both pSym and cryptic plasmids in HA12-1-12 were stable in different soybean hosts. However, the plasmids of HA7-2-2 underwent a series of genetic rearrangements.The results of plasmid visualization and total DNA hybridization showed that pSym in HA7-2-2 was more stable than ite cryptic plasmids, and the nod DABC and nif HDK genes harbored by pSym were highly conserved under symbiotic conditions. Moreover, nodulation tests revealed that no changes in nodulation or nitrogen fixation phenotype could be detected between HA7-2-2 and its derivatives with an altered plasmid profile.

关 键 词：快生型 大豆根瘤菌 内源质粒 稳定性 共生 培养 

分 类 号：Q939.114[生物学—微生物学]