东北地区玉米大斑病菌交配型组成及遗传多样性分析

Analysis of Mating Type Composition and Genetic Diversity of Setosphaeria turcica in Northeast China

明确东北地区玉米大斑病菌交配型组成情况及遗传结构,为进一步深入研究玉米大斑病的发生、流行及防控技术提供理论依据。利用交配型鉴定特异引物对2017年采自辽宁、吉林、黑龙江、内蒙古4个省(自治区)34个市县的57株玉米大斑病菌进行交配型测定,并采用相关序列扩增多态性(SRAP)分子标记技术对供试菌株进行遗传多样性分析。测定结果表明:东北地区玉米大斑病菌主要包括2种交配型,即仅含StMAT1-2基因的a交配型和仅含StMAT1-1基因的A交配型,且a交配型的比例(78.95%)明显高于A交配型(21.05%),表现出明显的不平衡现象。遗传多样性分析结果表明:从100对SRAP通用引物中筛选出多态性较好且稳定的8对引物组合,共扩增出64条条带,不同引物组合对供试菌株扩增条带数量不同,引物组合Me5/Em9和Me8/Em1扩增的条带数量最多,Me3/Em3扩增的条带数量最少,其中多态性条带44条,平均每个引物组合扩增出5.5个多态性条带,多态性位点比率为68.75%。UPGMA聚类分析显示,供试菌株遗传相似系数介于0.76~1.00,在阈值为0.82时,所有菌株被分为4个类群,表现出丰富的遗传多样性。SRAP划分结果表明:类群Ⅰ中菌株均为A交配型,a交配型菌株均聚集于类群Ⅱ中,说明玉米大斑病菌遗传类群和交配型之间存在密切关系,但二者均与菌株地理来源无明显相关性。

To clarify the mating types composition and genetic structure of Setosphaeria turcica in Northeast China, and provide a theoretical basis for further research on the occurrence, prevalence, and prevention and control techniques of Northern corn leaf blight.Specific primers for mating types identification were used to test the mating types of 57 isolates of S. turcica collected from 34 cities and counties in 4 provinces(autonomous regions) including Liaoning, Jilin, Heilongjiang and Inner Mongolia in 2017, and the genetic diversity of the tested isolates was analyzed by the sequence-related amplified polymorphism(SRAP) molecular marker technology.The results of mating types composition showed that S. turcica in Northeast China mainly includes two mating types, namely"a"mating type with only StMAT1-2 gene and"A"mating type with only StMAT1-1 gene, and the proportion of"a"isolates(78.95%)was significantly higher than that of"A"(21.05%), showing obvious imbalance. Genetic diversity analysis results showed that 8 pairs of primers with good polymorphism and stability were selected from 100 pairs of SRAP universal primers, and a total of 64 bands were amplified, different primer combinations had different numbers of amplified bands for the tested isolates, primer combinations Me5/Em9 and Me8/Em1 amplified the most number of bands, and Me3/Em3 amplified the least number of bands, of which 44 bands were polymorphic, the average number of polymorphic bands per primer combination was 5.5, and the ratio of polymorphic sites was 68.75%. UPGMA cluster analysis showed that the genetic similarity coefficient of the tested isolates ranged from 0.76 to 1.00, and when the threshold was 0.82, all isolates were divided into 4 groups, showing rich genetic diversity. The SRAP classification results showed that the isolates in group Ⅰ were all"A"mating type,"a"mating type isolates were all clustered in group Ⅱ, indicating that there is a close relationship between the genetic group and mating types of S. turcica, but both of them have no obvious correlation with the geographical origins of the isolates.