Clycine max (soybean) plants can be nodulated by fast-growing rhizobial strains of the genus Sinorhizobium as well as by slow-growing strains clustered in the genus Bradyrhizobium In the past research fast-growing rhizobia strains with different soybean cultivar specificities were i solated from various geographical regions.Most of these strains were clustered into the species Sinorhizobium fredii.The largest plasmid (pSfrHH103e) harbours genes for the production of diverse surface polysaccharides,such as exopolysaccharides (EPS),lipopolysaccharides (LPS),and capsular polysaccharides (KPS).The second largest plasmid (pSfrHH103d) is a typical symbiotic plasmid (pSym),carrying nodulation and nitrogen fixation genes.The model strain S.fredii HH103 was chosen for genomic sequencing,which is currently in progress.Starting from classification basis and main types of nodule and rhizobial strains the research status of HH103 was introduced,and the research direction in the future was forecasted.%大豆既可以与快生型根瘤菌又可以与慢生型根瘤菌共生固氮.在以往的研究中,已有很多从不同地区的大豆根部分离出来的快生型根瘤菌,这些快生型根瘤菌大多数属于费氏中华根瘤菌属.模式菌株费氏中华根瘤菌菌株HH103现被用于基因序列的研究.该研究从根瘤和根瘤菌的分类依据和主要类型入手,介绍了HH103的主要研究现状,并且讨论其研究方向.
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