瓜枝孢弱毒菌株基因组分析

Genome Analysis of Strains of Cladosporium cucumerinum with Low-pathogenicity Induced by High Temperature

经高温筛选到具有弱致病性的瓜枝孢菌株2R、3R。经稳定遗传特性试验表明,菌株2R经15代繁殖后弱致病性仍然得到稳定遗传。采用RAPD和AFLP技术在全基因组水平分析了高温诱导产生的瓜枝孢弱毒菌株的变化。结果表明AFLP技术可以有效地揭示弱毒菌株的DNA的变异,瓜枝孢经50℃高温处理后基因组发生了显著的变化。AFLP图谱分为三种:一种是弱毒菌株和野生型菌株的扩增谱带基本相同;另一种是弱毒菌株产生的谱带一部分与野生型菌株相同,同时出现新的扩增片段;第三种情况是弱毒菌株有新的DNA片段产生,但是与野生型菌株相同的大部分主带消失。256个AFLP引物组合在扩增2R/2Q和3R/3Q时(瓜枝孢弱毒菌株2R和3R,野生型菌株2Q和3Q),分别在2910和2216个位点上有DNA片段产生,2R与2Q以及3R与3Q的遗传相似性分别为24.81%和43.68%。

Low-pathogenicity strains 2R and 3R were screened out via high-temperature mutation. Genetic tests indicated that 2R was steady after 15 transferes. RAPD and AFLP analysis indicated that AFLP could effectively reveal the variation of genome of the strains with low-pathogenicity, and the DNA of the strains was sufficiently changed after treatment with 50℃. AFLP patterns amplified by different primer combinations showed three types. The first one was that from low-pathogenicity which was almost the same as its wild strain. The second was that most bands from DNA fragments of the low-pathogenicity strains were the same as those produced from wide types. The third one was that there were new DNA bands from wild strains. The genetic similarity between 2R and 2Q and between 3R and 3Q were 24.81% and 43.68 %, respectively. Our results indicated that the molecular variation involved in the low-pathogenicity of fungus induced by high temperature was rather complex. It was necessary to study the genetics of low-pathogenicity strains and molecular mechanism to provide useful information for biological control using the agents.