云南省玉米白斑病病原菌鉴定与品种田间抗性评价

Identification of the pathogen causing maize white spot and field evaluation of maize cultivars for resistance to the disease

为明确近年来云南省严重发生的玉米白斑病病原菌及不同玉米品种对玉米白斑病的抗性差异,2021年于云南省昆明市阿子营乡和曲靖市罗平县九龙镇采集病样,进行病斑组织分离纯化,通过形态学特征和分子生物学方法对病原菌进行鉴定,并在云南省曲靖市罗平县九龙镇采用田间自然发病方法对622份玉米品种的抗性进行鉴定。从2个采样地点的病叶中各分离出5株和9株菌株,经柯赫氏法则验证,确定了菌株WS-1、WS-191为白斑病致病菌;经形态学观察以及基于ITS、rpb2、tub2和LSU基因序列构建的系统发育树分析结果确定其分类学种名为宽颈附球菌Epicoccum latusicollum。田间抗病性试验结果表明,在622份区域试验品种中对白斑病表现高抗、抗病、中抗、感病和高感的品种分别为4、184、216、186和32份,分别占品种总数的0.64%、29.58%、34.73%、29.90%和5.14%。

This study was aimed to identify the causal agent of maize white spot disease occurred recently in Yunnan Province,and to clarify the differences in resistance of different maize cultivars to the disease.Symptomatic samples were collected in Aziying Township,Kunming City,and Jiulong Town,Luoping County,Qujing City,Yunnan Province in 2021.The lesion tissue was surface sterilized and pathogen was isolated,purified,and identified with morphological and molecular biology characteristics.In addition,622 maize cultivars were evaluated for resistance against this disease in Jiulong Town in the field without artificial inoculation.Total of five(Aziying)and nine(Jiulong)strains were isolated from the symptomatic leaves at the two sampling sites,respectively.The pathogenicities of the strains were verified by Koch’s postulate,and strains WS-1 and WS-191 were re-isolated from the pathogenicity test and verified as the causal pathogens of white spot disease.A phylogenetic tree was constructed based on ITS,rpb2,tub2 and LSU sequences and confirmed that WS-1 and WS-191 were located within the same clade as Epicoccum latusicollum.The field disease resistance study suggested that among the 622 regional tested cultivars;4,184,216,186 and 32 cultivars displayed high resistance,resistance,intermediate resistance,susceptible and high susceptibility to maize white spot,respectively,accounting for 0.64%,29.58%,34.73%,29.90%and 5.14%of the total tested varieties.