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紫云英根瘤菌菌株107 exo基因簇的遗传互补分析

黄建斌, 王江海, 华征, 粟文英, 宋鸿遇

中科院上海植物生理研究所.上海 200032

摘要

紫云英根瘤菌菌株107经Tn5插入诱变,得到12株胞外多糖缺陷型变种,以质粒pMN2为载体,从其中7株EPS~(-)变种内分别构建了7个R-prime质粒(exoR^),大部分变种的EPS~(-)表型可被exoR^互补,恢复野生型表型(EPS~(+))。互补表明,12株EPS~(-)变种可分为6个不同的互补群,其中5个在遗传上连锁。exoR^酶切分析,除exoR^-02,exoR^-04外,其余5只的外源片段均整合于pMN2的两同向重复序列IS21之间。

关键词： 遗传分析; 紫云英根瘤菌; exo基因簇; 胞外多糖

Genetic analysis of a cluster of exo genes required for EPS synthesis in Rhizobium astragalus

Huang Jianbing, Wang Jianhai, Hua Zhen, Shu WenYin, Song Hongyu

Shanghai Institute of Plant Physiology,The Chinese Academmy of Sciences.Shanghai 200032

Abstract

Twelve exopolysaccharide(EPS)-deficient(Exo) mutants were isolated after Rhizobium astragalus strain 107 was subjected to transposon Tn5 mutagenesis.Using the broad host range vector plasmid pMN2,a kanamycin-sensitive derivative of plasmid R68.45,seven R-primmes (exoR^)from seven EPS~(-) mutants of Rhizobium astragalus strain 107 were isolad.Each exoR^ plasmid carried a specific Tn5 insertion site and its flanking fragment coding for exopolysaccharide synthesis. When these exoR^ plasmids were introduced back into the twelve mutants,exoR^ plasmids were able to complement the EPS~(-) phenotype of most mutants. Based on complementation analysis, twelve EPS~(-) mutants were classified into six distinct complementation groups. Five of the six exoloci were genetically linked.By restriction enzyme analysis, it was shown that in all exoR^ plasmids but exoR-02 and exoR^-4,the foreign DNA fragments were integrated between the tandem repeat sequence IS21.The mobilization of megaplasmid and Southern hybridization experiments showed that the probeexctly hybridized the total DNA of these strains with the pRa 107b. It means that the five linked exo loci were located on the megaplas-mid pRa107b.

Key words: Genetic analysis;Rhizobium astragalus;Exocluster;Exoploysaccharide

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引用本文：

黄建斌, 王江海, 华征, 粟文英, 宋鸿遇. 紫云英根瘤菌菌株107 exo基因簇的遗传互补分析[J]. 生理学报 1996; 48 (2): .

Huang Jianbing, Wang Jianhai, Hua Zhen, Shu WenYin, Song Hongyu. Genetic analysis of a cluster of exo genes required for EPS synthesis in Rhizobium astragalus. Acta Physiol Sin 1996; 48 (2): (in Chinese with English abstract).