甘肃玉米鞘腐病病原菌种群多样性及优势种遗传多样性分析

Analysis on the Population Diversity of Pathogens from Maize Sheath Rot in Gansu Province and Genetic Diversity of Dominant Pathogens

为明确甘肃省玉米鞘腐病致病菌种类及优势病原菌的遗传多样性,2022—2023年在甘肃省陇东、陇南等不同地区采集60份玉米鞘腐病病样进行组织分离,通过形态学观察、分子生物学鉴定及致病性测定相结合的方法,对其病原进行鉴定。结果表明,共获得166株镰孢菌菌株,分别为拟轮枝镰孢(Fusarium verticillioides)(73.5%)、层出镰孢(Fusarium proliferatum)(13.3%)、胶孢镰孢(Fusarium subglutinans)(5.4%)、温孢镰孢(Fusarium temperatum)(3.6%)、木贼镰孢(Fusarium equiseti)(1.8%)、布氏镰孢(Fusarium boothii)(1.2%)和燕麦镰孢(Fusarium avenaceum)(1.2%),其中拟轮枝镰孢(F.verticillioides)为优势病原菌。采用简单序列重复区间(ISSR)分子标记技术对72株拟轮枝镰孢进行遗传多样性分析,结果显示25条引物共扩增出193条清晰条带,其中192条为多态性条带,比例为99.48%,4个生态区Shannon’s信息指数和Nei’s遗传多样性指数平均为0.4612和0.3087,遗传相似度、遗传距离集中在0.9258~0.9510、0.0503~0.0771,证明拟轮枝镰孢存在较高的遗传多样性。陇东地区菌株遗传多样性最为丰富,且和陇南地区的遗传相似度最高,为0.9501,遗传距离最小,为0.0503,陇中地区次之。在遗传相似系数为0.67时,供试菌株可划分为9个类群,同一地理来源的菌株分布在不同的ISSR类群中,说明玉米鞘腐病优势病原菌拟轮枝镰孢ISSR类群的划分与地理来源没有明显的相关性。本研究结果可为甘肃省玉米鞘腐病的科学防治提供理论依据。

In order to clarify the pathogen species and the genetic diversity of dominant pathogens of maize sheath rot in Gansu Province,sixty samples of maize sheath rot were collected from the Longdong region,Longnan region and other regions of Gansu Province from 2022 to 2023 for tissue isolation,and the pathogen was identified by morphological features,molecular biological identification,and pathogenicity tests.The results showed that a total of 166 Fusarium strains were obtained.They were F.verticillioides(73.5%),F.proliferatum(13.3%),F.subglutinans(5.4%),F.temperatum(3.6%),F.equiseti(1.8%),F.boothii(1.2%),and F.avenaceum(1.2%).Among them,F.verticillioides was the dominant pathogen.The genetic diversity of 72 strains of F.verticillioides was analyzed by ISSR molecular marker technology.The results showed that a total of 193 clear bands were amplified by 25 primers,of which 192 were polymorphic bands,with a ratio of 99.48%.The average Shannon’s information index and Nei’s genetic diversity index of the four ecoregions were 0.4612 and 0.3087,respectively.The genetic similarity and genetic distance between the four geographical populations were concentrated at 0.9258 to 0.9510 and 0.0503 to 0.0771,which indicated that F.verticillioides existed at a higher level of genetic diversity.The genetic diversity of the strains in the Longdong region was the most abundant and had the lowest genetic distance of 0.0503 and the highest genetic similarity of 0.9501 with Longnan region,followed by the Longzhong region.When the genetic similarity coefficient was 0.67,the geographic populations of F.verticillioides were divided into nine groups and the strains of the same ecoregion were distributed in distinct ISSR groups,indicating that the division of ISSR groups of F.verticillioides had no significant correlation with the geographical origin.The results of this study can provide a theoretical basis for the scientific control of maize sheath rot in Gansu.