四川盆地核桃黑斑病病原菌的分离、鉴定与核桃抗病性评价

为鉴定引起四川盆地地区核桃黑斑病的病原菌,采用组织分离法对病原菌进行分离,利用柯赫氏法则验证其致病性,依据菌株形态学和基于16S rDNA基因序列分析对病原菌进行鉴定;同时,利用分离的菌株对18个栽培品种(无性系)进行抗病性评价。结果表明,分离菌株的菌落形态与黄单胞杆菌属(Xanthomonas)相似,其16S rDNA序列与树生黄单胞杆菌(X. arboricola)的(登录号为KP340804.1)同源性高达99%,因此,将引起四川盆地地区核桃黑斑病的病原菌鉴定为树生黄单胞杆菌。18个核桃栽培品种(无性系)的田间侵染发病率和病情指数分别为35.07%～78.57%和17.71%～51.96%,变异系数分别为17.62%和28.78%,并以此为基础评价出5个高抗病品种(无性系)。这为核桃黑斑病致病机理研究和抗病新品种的选育奠定基础。

Isolation and Identification of Walnut Blight Pathogens and Resistance Evaluation of Walnut in Sichuan Basin Area

In order to identify the pathogens of walnut blight in Sichuan Basin Area, the pathogens was isolated by using tissue isolation method, and the pathogenicity was tested using Koch''s postulates. The pathogen was identified based on morphological characteristics and sequence analysis of 16S rDNA, and the resistance of 18 cultivars (clones) of Juglans regia was evaluated through field infection using the isolated strain. The results showed that the morphology of isolated pathogen were similar with Xanthomonas, which sequence of 16S rDNA showed 99% similarity with X. arboricola (GenBank No. KP340804.1). Therefore, X. arboricola was identified as the pathogen caused the walnut blight in Sichuan basin area. The incidence and disease index of 18 walnut cultivars (clones) were ranged from 35.07% to 78.57%, and 17.71% to 51.96%, with the coefficient of variation of 17.62% and 28.78%, respectively. Based on the resistance evaluation, five highly resistance cultivars (clones) were selected. Therefore, these would provide basis for pathogenesis mechanism of walnut blight and resistance breeding.