Division of Rhizobitoxine-Producing and Hydrogen-Uptake Positive Strains of Bradyrhizobium japonicum by nifDKE Sequence Divergence
Division of Rhizobitoxine-Producing and Hydrogen-Uptake Positive Strains of Bradyrhizobium japonicum by nifDKE Sequence Divergence
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利用 nifDKE 序列分歧对日本慢生根瘤菌产根瘤菌素和吸氢阳性菌株的划分
DOI：
10.1093/oxfordjournals.pcp.a077885
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发表时间：
1990
影响因子：
4.9
通讯作者：
K. Minamisawa
中科院分区：
文献类型：
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作者：
K. Minamisawa
用25株慢生根瘤菌USDA 110的nifDK和nife基因的探针DNA进行杂交，测定了其根瘤菌毒素的产生、吸氢量(Hup)和胞外多糖(EPS)的组成。根据nifDKE内和周围碱基替换程度的估计，日本血吸虫菌株明显分为两个明显不同的类群，分别命名为I型和II型。此外，这两种基因型、根瘤菌毒素的产量和EPS组成之间存在着严格的相关性。基因I菌株不产生根瘤菌毒素和由葡萄糖、甘露糖、半乳糖、4-甲基半乳糖和半乳糖醛酸组成的EPS，而基因II菌株产生根瘤毒素和由鼠李糖和4-O-甲基葡萄糖醛酸组成的EPS。将25株HUP菌株基因组DNA的Hind III酶切片段与日本血吸虫吸氢酶结构基因的探针DNA杂交。在23株野生型菌株中，Hup菌株产生了一条5.9kb的条带，该条带在高要求的条件下与探针杂交，而Hup“菌株没有产生该条带。这些结果表明，I型和II型是两个高度分化的进化系，它们定义了不同表型的显著分化，如根瘤菌毒素的产生、EPS组成和吸氢。
Genomic digests from 25 strains of Bradyrhizobium japonicum, for which the phenotypes have been determined with respect to production of rhizobitoxine, hydrogen uptake (Hup) and composition of extracellular polysaccharide (EPS), were hybridized with probe DNAs of the nifDK and nifE genes of B. japonicum USDA 110. The degree of the estimated base substitution in and around nifDKE clearly divided the strains of B. japonicum into two markedly divergent groups, which were designated as genotype I and II. Moreover, a strict correlation was observed between these genotypes, production of rhizobitoxine and EPS composition. The genotype I strains produced no rhizobitoxine and an EPS composed of glucose, mannose, galactose, 4-Omethyl galactose and galacturonic acid, whereas the genotype II strains produced rhizobitoxine and an EPS composed of rhamnose and 4-O-methyl glucuronic acid. Hup strains were confined exclusively to the genotype I. Hind III digests of genomic DNAs from the 25 strains were hybridized with probe DNA of structural genes for the uptake hydrogenase from B. japonicum. In 23 wild-type strains, Hup strains generated a 5.9-kb band that hybridized to the probe under high-stringency conditions, while Hup" strains did not generate the band. These results suggest that the genotypes I and II are two highly divergent evolutionary lines that define a marked division of various phenotypes, such as production of rhizobitoxine, EPS composition and hydrogen uptake.