莴笋链格孢叶斑病病原鉴定及室内生防菌剂筛选  

Identification and Indoor Biocontrol Agents Screening of Alternaira Leaf Spot of Lettuce

作　　者：朱启寒 何剑鹏 张晓阳 李庚花[1] 刘冰[1] 熊桂红 蒋军喜[1] ZHU Qihan;HE Jianpeng;ZHANG Xiaoyang;LI Genghua;LIU Bing;XIONG Guihong;JIANG Junxi(College of Agronomy,Jiangxi Agricultural University,Nanchang 330045,China;Jiujiang Agricultural Technology Promotion Center,Jiujiang,Jiangxi 332000,China)

机构地区：[1]江西农业大学农学院,江西南昌330045 [2]江西省九江市农业技术推广中心,江西九江332000

出　　处：《江西农业大学学报》2023年第2期395-403,共9页Acta Agriculturae Universitatis Jiangxiensis

基　　金：国家自然科学基金项目(31460452)。

摘　　要：【目的】明确江西省南昌市郊区莴笋链格孢叶斑病病原菌种类,筛选出能有效防治该病害的生防菌剂。【方法】采用组织分离法对莴笋链格孢叶斑病进行病原菌分离纯化,选择代表性菌株WS1作为供试菌株进行孢子悬浮液刺伤接种,再对接种发病的病斑进行病原菌再分离,以完成柯赫氏法则验证,最后对分离所得病原菌进行形态学鉴定;采用真核生物核糖体基因转录间隔区rDNA-ITS以及过敏原基因Alt a1分别对病原菌进行PCR扩增和序列测定,使用BLAST软件,在GenBank中进行序列同源性比对,并利用MegA 7.0软件构建系统发育树,以对病原菌进行分子鉴定。采用对峙培养法测定8种常见市售生防菌剂对该病原菌的室内抑菌效果。【结果】共分离获得23个培养性状一致的链格孢菌株,其对莴笋叶片均具有致病性。病原菌在PDA培养基上菌落圆形,中间灰褐色,边缘白色,菌丝体茂密呈绒状,后期正面中央颜色加深成暗青褐色,背面呈黑褐色,菌落平均生长速度10.86 mm/d。分生孢子倒棍棒形或椭圆形,淡褐色至褐色,具0~6个横隔、0~3个纵隔和0~2个斜隔,孢身大小14.60~40.09μm×6.61~14.44μm。短喙柱状或锥形,淡褐色,大小1.84~8.29μm×2.60~4.35μm。分生孢子链生于分生孢子梗上,主链一般不超过10个孢子,支链不超过5个孢子。其培养性状和形态特征与文献中对交链格孢(Alternaria alternata)的描述相吻合。测定的rDNA-ITS和Alt a1基因的序列长度分别为570 bp和472 bp,序列登录号分别为OP161641和OP185144,与GenBank中交链格孢对应序列的同源性均为100%,并在系统发育树上处于同一个分支且支持率为99%。通过形态学和分子生物学将此病原菌鉴定为交链格孢(A.alternata)。在室内生防菌剂筛选试验中,地衣芽孢杆菌、荧光假单胞菌、解淀粉芽孢杆菌、枯草芽孢杆菌、侧孢芽孢杆菌、蜡质芽孢杆菌、胶质芽孢杆菌和巨大芽孢杆菌[Objective]The objective of this study was to identify the pathogen of Alternaria leaf spot of lettuce in the suburb of Nanchang City,Jiangxi Province,in order to screen biocontrol agents that can effectively control the disease.[Method]Infected lettuce leaves were used for isolating and purificating the pathogen.In order to fulfil Koch’postulates,pathogenicity test was done by artificially inoculating healthy leaves of lettuce with spore suspension of representative isolates WS1,then the pathogen was reisolated from the newly produced lesions,and finally the pathogen was identified by morphology.The pathogenic bacteria were amplified by PCR and sequenced by using rDNA-ITS and allergen gene Alt a1.For pathogenic identification on molecular level,nucleotide sequence homology was compared in GenBank using BLAST software,and phylogenetic tree was constructed by the neighbor-joining method using MegA 7.0 software.The antifungal effect of 8 common commercial biocontrol agents was detected by confrontation culture method.[Results]A total of 23 strains of Alternaria with the same cultural characteristics were isolated,which were pathogenic to lettuce leaves.The colonies on potato dextrose agar(PDA)were round,grayish brown in the middle and white on the edge,and the mycelium was dense and fluffy.The central color of the front was deepened to dark cyan and the back was dark brown in the later stage,the colony average growth rate reached 10.86 mm/d.The conidia were obclavate or oval,light brown to brown,0-6 transverse septa,0-3 longitudinal septa and 0-2 oblique septa,with size of 14.60-40.09μm×6.61-14.44μm.Short beaks were columnar or conical,light brown,with size of 1.84-8.29μm×2.60-4.35μm.The conidia were produced on the conidiophores and were attached in a chain form.The main chains were generally not more than 10 spores,and the branch chains were not more than 5 spores.The culture characteristics and morphological characteristics are consistent with the description of Alternaria alternata in the literature.The

关 键 词：莴笋链格孢叶斑病 病原鉴定 交链格孢 生防菌剂筛选 

分 类 号：S436.36[农业科学—农业昆虫与害虫防治]