华癸中生根瘤菌共生基因exo56的克隆和功能初步分析  

Cloning and Function Analysis of Symbiotic Gene exo56 of Mesorhizobium huakuii 7653R

作　　者：程国军[1] 陈大松[1] 李友国[1] 谢福莉[1] 周俊初[1] 

机构地区：[1]华中农业大学农业微生物学国家重点实验室

出　　处：《华中农业大学学报》2008年第4期483-486,共4页Journal of Huazhong Agricultural University

基　　金：科技部教学实验用微生物资源平台建设项目(2005DKA21208-6);中南民族大学自然科学基金重点项目(YZZ06013)资助

摘　　要：利用Tn5-sacB转座子随机插入突变的方法,从Mesorhizobium huakuii7653R的400个突变株中筛选获得1个共生缺失突变株HK56。使用热不对称交错PCR(TAIL-PCR)的方法从M.huakuii7653R中克隆了exo56序列。exo56全长969 bp,编码322个氨基酸,其编码产物Exo56与糖基转移酶2个家族的成员有很高的相似性,糖基转移酶为胞外多糖合成所必需。盆栽结果表明,exo56基因突变株只能形成少量的不固氮根瘤。Four hundred mutants were obtained from Mesorhizobium huakuii 7653R using Tn5-sacB insertion mutagenesis. Symbiotic mutant HK56 was screened by plant nodulation experiments. The DNA sequence of exo56 was determined by thermal asymmetric interlaced PCR （TAIL-PCR）. exo56 has a length of 969 bp and encodes a protein of 322 amino acids. Exo56 of M. huakuii 7653R showed high sequence similarity to the member of glycosyl transferase family 2 and is necessary to exopolysaccharides synthesis. Plant studies showed that exo56 mutant formed little ineffective nodules.

关 键 词：华癸中生根瘤菌 共生基因 克隆与鉴定 胞外多糖 

分 类 号：S154.38[农业科学—土壤学]