为明确我国北方玉米主要产区玉蜀黍黑粉菌交配型a位点鉴别及其遗传多样性水平，利用特异性引物对2017年采自7个省（自治区）的84份玉米瘤黑粉病菌进行交配型a位点鉴别，并采用相关序列扩增多态性（ISSR）分子标记技术对供试菌株进行遗传多样性分析。试验结果显示：玉蜀黍黑粉菌交配型a位点基因型种类主要有三种：mfa1、mfa2和mfa1+mfa2，84株菌株中，mfa1基因型和mfa1+ mfa2基因型均有31株，占鉴定株数的36.9%；22株为mfa2位点，占鉴定株数的26.2%。通过筛选出的 8 条ISSR引物共扩增出61条清晰条带，特异性条带55条，多态性位点所占比例为90.2%。UPGMA聚类分析结果表明，供试菌株遗传相似系数介于0.59-0.92，在遗传相似系数为0.65时供试菌株被分为6个类群，表现出丰富的遗传多样性。ISSR揭示的玉蜀黍黑粉菌遗传多样性、交配型a位点基因型以及地理来源之间的关系分析结果表明菌株的遗传类群和交配型a位点基因型之间无密切关系，并且二者与菌株地理来源也无明显相关性。

To clarify the mating type a locus and the genetic diversity of Ustilago maydis in the main corn producing areas in North China. The mating type a locus identification and genetic diversity analysis of 84 corn smut isolates collected from 7 provinces (autonomous regions) were carried out by the inter simple sequence repeat (ISSR) molecular marker technology. The results showed that there were three genotypes of mating type a locus of Ustilago maydis, mfa1, mfa2 and mfa1+ mfa2. In the 84 isolates, mfa1 genotype and mfa1+ mfa2 genotype both had 31 isolates, accounting for 36.9 % of the total; 22 isolates were mfa2, accounting for 26.2 %. The results demonstrated that the 55 specific bands were amplified by 8 primers in the 61 bands, the proportion of loci was 90.2%. UPGMA cluster analysis showed that the genetic similarity coefficient of the tested isolates ranged from 0.59 to 0.92, and when the threshold was 0.65, all isolates were divided into 6 groups, showing rich genetic diversity. The analysis results of the relationship among the genetic diversity, genotypes of mating type a locus and geographical origins of Ustilago maydis revealed by ISSR indicated that there was not a close relationship between the genetic groups and genotypes of mating type a locus of the tested isolates, and there was no obvious correlation between them and the geographical origins.

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