我国长江流域和南方地区花生青枯菌遗传多样性分析

Study on genetic diversity of bacterium Ralstonia solanacearum in peanut in Yangtze River Valley and southern China

为明确不同青枯菌的遗传多样性和其在花生植株上的致病力差异,采用国际上新的青枯菌演化型分类模式,对从我国长江流域和南方地区9个花生种植区分离的95株花生青枯菌Ralstonia solanacearum菌株进行遗传多样性分析,基于内源葡聚糖酶基因egl对青枯菌进行系统发育研究,并对供试青枯菌的致病力进行测定。结果表明,所有95株菌株均属于青枯菌演化型I型,即亚洲分支类型。在序列变种分类上,所检测的9个花生种植区中有8个种植区的花生青枯菌菌株属于序列变种14,仅有1个种植区(广西壮族自治区贺州市)的花生青枯菌菌株属于序列变种48,表明我国长江流域和南方地区花生青枯菌群体遗传多样性水平较低。青枯菌致病力测定结果表明,来自赣州市的菌株GZ-1、贺州市的菌株HZ-2和宜昌市的菌株YC接种到花生植株14 d后,花生的病情指数分别为43.8、75.0和87.5,而来自其它6个花生种植区的菌株接种花生后,其病情指数均为100.0,表明菌株GZ-1和HZ-2的致病力较弱,而其它7个花生种植区代表性菌株的致病力均较强。

To illuminate the genetic diversity and pathogenic variation of different Ralstonia solanacearum strains in peanut Arachis hypogaea, the new hierarchical classification scheme of the R. solanacearum species complex comprising of species, phylotypes, and sequevars was applied to analysis of genetic diversity of 95 strains of R. solanacearum from nine peanut growing areas in Yangtze River Valley and southern China. The results showed that all strains belonged to phylotype I(Asia type). The phylogenetic tree based on the nucleotide sequences of egl from R. solanacearum peanut strains and reference strains was generated to divide them into sequevars. R. solanacearum strains isolated from eight of nine areas belonged to sequevar 14, only the strains obtained from Hezhou, Guangxi belonged to sequevar 48. The results indicated that the level of genetic diversity of R. solanacearum strains from peanut was low in Yangtze River Valley and southern China. Fourteen days after infection, the disease index of GZ-1, HZ-2 and YC strains were 43.8, 75.0 and 87.5, respectively. The disease index of represent strains from the other six peanut growing areas were all 100.0. The results of pathogenic tests of R. solanacearum strains demonstrated that the pathogenicity of GZ-1 and HZ-2 strains were weak, while the other represent strains isolated from seven areas showed more virulent.