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通过交配型和甲霜灵抗性以及线粒体DNA单倍型、SSR和AFLP基因型分析对40个超级生理小种菌株进行了遗传多样性分析。在被测菌株中发现了A1、A2和自育3种不同类型的交配型。其中,A1和自育型菌株数量多,分别为21株和14株,而A2交配型仅5株。甲霜灵抗性测定检测出高抗菌株26株,敏感菌株14株。线粒体DNA单倍型测定出Ia型和IIa型两种,比例接近1:1。基于5个基因座被测40个超级生理小种菌株共鉴定出了7种SSR基因型。利用6对荧光引物共检测到258条AFLP谱带,其中多态性谱带204条,多态性为79.1%。将供试的40个菌株划分为38个基因型,几乎每个菌株都为1个特有基因型。而且,我国南方和北方超级生理小种群体存在着明显的遗传差异。结果表明我国致病疫霉超级生理小种具有丰富的遗传多样性,可以推断致病疫霉中的任何小种都可在多个抗病基因的强大选择压力下,在短时间内通过与之对应的无毒基因快速突变而成为超级生理小种。当前对致病疫霉生理小种的鉴定及监测对生产上利用抗病品种防控晚疫病的指导意义不大。
The genetic diversity of 40 super-physiological races was analyzed by mating and metalaxyl resistance and mitochondrial DNA haplotypes, SSR and AFLP genotyping. In the tested strains were found A1, A2 and self-education of three different types of mating type. Among them, the number of A1 and self-bred strains were more than 21 strains and 14 strains, respectively, while the A2 mating type only 5 strains. Metalaxyl resistance assay detected 26 highly resistant strains and 14 susceptible strains. Mitochondrial DNA haplotypes identified two types of Ia and IIa at a ratio of nearly 1: 1. Seven SSR genotypes were identified based on the 40 super-physiological races tested at the five loci. A total of 258 AFLP bands were detected using 6 pairs of fluorescent primers, of which 204 bands were polymorphic with a polymorphism of 79.1%. The 40 strains tested were divided into 38 genotypes, almost every strain was a unique genotype. Moreover, there are obvious genetic differences in the racial population of the South and North China. The results showed that there was a rich genetic diversity in the phytopathogenic races of Phytophthora infestans in China. It could be inferred that any races of P. infestans could be infected by the strong selection pressure of multiple resistance genes in a short period of time The corresponding non-toxic genes rapidly mutate and become super-physiological races. The current identification and monitoring of P. infestans physiological races is of little significance in guiding the use of resistant varieties in controlling late blight in production.