豌豆根瘤菌ohrB基因的抗氧化和共生固氮表型  

Antioxidation and symbiotic nitrogen fixation phenotype of ohr B gene in Rhizobium leguminosarum

作　　者：田梦洋[1] 何冬兰[1] 李晓华[1] 周艳琳[1] 曾小波[1] 程国军[1] 

机构地区：[1]中南民族大学生命科学学院,武汉430074

出　　处：《华中农业大学学报》2016年第3期54-60,共7页Journal of Huazhong Agricultural University

基　　金：湖北省自然科学基金项目(2014CFB914);中南民族大学中央高校基本科研业务费专项(CZW15023和CZW14001)

摘　　要：采用基因敲除构建豌豆根瘤菌ohr B基因突变株,研究突变株的抗氧化和共生固氮表型。结果表明:ohr B基因不影响菌株在自生培养条件下的生长能力,但对氢过氧化枯烯(cumene hydroperoxyde,Cu OOH)、过氧化氢(H2O2)、次氯酸钠(Na Cl O)等氧化物敏感,且在Cu OOH胁迫下,相比野生型菌株,突变株的存活率显著下降。荧光定量RT-PCR结果显示,豌豆根瘤菌ohr B基因表达不受H2O2诱导,且ohr B基因的缺失对其他抗氧化基因的表达没有影响。共生实验表明,ohr B基因对根瘤菌共生固氮能力及根际定殖能力没有影响,但在7 d瘤龄的豌豆根瘤类菌体中表达水平显著提高,并对根瘤菌结瘤能力有影响。ohr B基因虽对豌豆根瘤菌的自生生长、共生固氮、根圈定殖没有影响,但在抗氧化及竞争结瘤中发挥重要作用。Through homologous recombination, a Rhizobiurn legurninosarum ohrB mutant was constructed, and its antioxidation and symbiotic nitrogen fixation phenotypes were studied.The growth ability of the ohrB mutant was the same as the wild type under free-living condition.However, cells of the ohrB mutant were sensitive to CuOOH, H2O2 and NaClO.The ohrB mutant was highly sensitive after the short exposure to CuOOH.The results of quantitative real-time PCR showed that the expression of ohrB was not stimulated by exogenous H2O2.The transcription of other antioxidant genes in the ohrB mutant strain was not changed.The ohrB mutant had normal nitrogenase activity and the same coloniza- tion ability in the pea rhizosphere compared to the wild type. However, the ohrB gene in 7-day-old pea bacteroids was expressed significantly higher than that in free-living cells.The competition nodule ability of ohrB mutant was reduced compared to that of the wild type.It is indicated that ohrB is essential in an tioxidation and competition of nodule ability, playing an important role in antioxidation and symbiosis.

关 键 词：豌豆根瘤菌 ohrB突变株 抗氧化活性 基因表达 共生固氮 

分 类 号：S154.381[农业科学—土壤学]