大白菜与甘蓝寄生霜霉菌的致病性与rDNA-ITS序列分析

Pathogenicity and rDNA-ITS Sequences Analysis of the Oomycete Hyaloperonospora parasitica Parasiting on Chinese Cabbage and Cabbage

霜霉菌是一种在十字花科作物中寄主范围很广的专性寄生菌。本研究综合运用病菌形态学观察、病菌致病性测试和rDNA-ITS序列分析三种方法对北京地区的大白菜和甘蓝寄生霜霉菌进行比较,以期发现二者的进化关系。结果显示:两种病原菌在形态学上没有明显区别;但是对大白菜的致病力具有显著差异:大白菜霜霉菌对大多数参试的大白菜材料具有致病性,而甘蓝霜霉菌只是诱导大多数大白菜材料产生过敏反应,对个别易感大白菜材料具有较弱致病力;将rDNA-ITS序列提交至NCBI,大白菜和甘蓝霜霉菌的rDNA-ITS序列登录号分别为JF975613和JF975614,序列比对发现二者的序列一致性高达99.59%;利用19个十字花科霜霉病菌的ITS序列构建系统进化树,结果表明二者与寄生在甘蓝和甘蓝型油菜上的霜霉菌以100%的支持率聚在同一分支。

The oomycete Hyaloperonospora parasitica （Pets. ex Fr.） is an obligate biotroph infecting a wide range of host species in the family Cruciferae. In this study, the pathogens parasiting on Chinese cabbage （Brassica rapa ssp. pekinensis） and cabbage （B. oleracea） in Beijing area were analysed by morphological characteristics, pathoge- nicity test and the internal transcribed spacer （ITS） sequence of nuclear ribosomal DNA. The two isolates showed morphologically similar on conidiophores and branches, but significant difference in pathogenicity. The rDNA-ITS sequences of the pathogens parasiting on Chinese cabbage and cabbage were submitted to GenBank. The accession numbers were JF975613 and JF975614, respectively. Sequences alignment indicated that a very high similarities of 99.59% was gotten between the two rDNA-ITS sequence. 19 Hyaloperonospora isolates from Cruciferae were used for phylogenetic tree construction. JF975613 and JF975614 were closely relative with Hyaloperonospora brassicae parasiticaing on B. napus and B. orleace with hundred percent support rate.