豇豆轮纹病病原菌鉴定及ITS分析

为了解豇豆轮纹病病原,本研究采用形态观察、分子鉴定和系统进化分析的方法,对采自海口、澄迈、定安、文昌、万宁、陵水、三亚、乐东、东方、五指山等10个市县的豇豆轮纹病病样,进行了病原鉴定和ITS分析。结果表明:病原分离物具有多主棒孢霉(Corynespora cassiicola)的形态特征。其分生孢子梗褐色,数根丛生或单生,不分枝,直立或弯曲;分生孢子顶生,单生,倒棍棒形、圆柱形,正直或弯曲,褐色、淡橄榄色,具多个隔膜,顶部稍钝,基部有明显的脐。进一步序列分析发现其与NCBI数据库中多主棒孢霉(C.cassiicola)的多条ITS序列相似性达99%以上;系统进化树上,全部分离物聚在一个进化分支上,遗传距离近,差异极小;与对照豇豆炭疽病菌在不同的进化分支上,遗传距离远。综合形态学和ITS分析,将豇豆轮纹病病原鉴定为多主棒孢霉(C.cassiicola)。研究结果为明确豇豆轮纹病病原遗传多样性、成灾机理和防治技术提供参考依据。

Pathogenic Identification and ITS Analysis of Cowpea Rotational Disease

In order to under stand the pathogens of cowpea rotational disease,several samples of cowpea rotational disease were collected from Haikou,Chengmai,Ding’an,Wenchang,Wanning,Lingshui,Sanyan,Ledong,Dongfang,Wuzhishan and so on.Then the methods of morphological observation,molecular identification and phylogenetic analysis were used to identify pathogen and analyze ITS region.The results showed that the pathogen separation had typical morphological characteristics of Corynespora cassiicola.The conidiophores were brown,some were fascicled,the others were solitary.All of the conidiophores were unbranched,erect or curved;The conidia were terminal,solitary,inverted stick,cylindrical,straight or curved,brown or pale olive,with many dissepiment.The conidia were obtuse at the top and had an obvious hilum at the base.Futher sequence analysis showed that the similarity of ITS sequences to those of C.cassiicola in NCBI database were more than 99%.In the phylogenetic analysis,all the ITS sequences of isolates and C.cassiicola gathered on the same branch with the closer genetic distance,and the difference was smaller.The genetic distance was far from the control of cowpea anthracnose on different evolutionary branches.Together with morphological characteristics and analysis of ITS sequences and phylogentic,the pathogen of cowpea rotational disease was identified as C.cassiicola.These research results provided a reference for studying genetic diversity,disaster mechanism and control technology of cowpea rotationa disease.