李小霞　肖仲久　许艾斌　徐刚红

摘 要 近年在贵州省苏铁各栽培地发现一种叶枯病害，为明确其致病菌，采集苏铁叶枯病叶片样本数份，并对病原菌进行形态观察、致病性测定及rDNA-ITS序列分析。结果表明：经分离纯化获得的病原菌，通过柯赫氏法则，接种后出现的病害症状与直接采集到的病害标样症状一致，确定其为致病菌；对病原菌进行传统的形态学观察，结果显示病原菌分生孢子器和分生孢子的形态与拟茎点霉一致；将待测菌株rDNA-ITS序列与GenBank中相关菌株ITS序列进行同源性比较，结果显示该菌株与Phomopsis vaccinii（GenBank登陆号为：KC488259，JX846914）的同源性达97%。结合病原菌形态学特征及株rDNA-ITS序列（GenBan登录号：JN417709）特征，确定苏铁叶枯病病原菌为Phomopsis cycadis.

关键词 苏铁；拟茎点霉；病原菌

中图分类号 S791.11 文献标识码 A

Abstract Leaf blight on Cycas revoluta Thunb was discovered in Guizhou Province recently. The objective of the study was to identify the pathogen. The Cycas Leaf blight standard samples were collected and the pathogen was identified by morphology， pathogenicity and ribosomal DNA-ITS. The results showed that the isolated fungus was used for departments law of disease and syndrome. Disease symptoms after inoculation were the same as that on the collected samples，which showed the fungus was the pathogen. The pycnidia and conidiamorphology of the pathogen were similar to that of Phomopsis. Comparing the measured sequence with the related sequence of Phomopsis vaccinii（No：KC488259，JX846914） in GenBank， the homology was 97%. According to its characteristics of morphology and sequence analysis of the internal transcribed spacer region of the ribosomal DNA（ITS）（No：JN417709）the pathogen was identified as Phomopsis cycadis.

Key words Cycas revoluta Thunb；Phomopsis；Pathogen

doi 10.3969/j.issn.1000-2561.2014.10.030

苏铁（Cycas revoluta Thunb.）系苏铁科苏铁属常绿乔木，起源于3亿年前的晚石炭纪，是现存最古老最原始的种子植物之一[1-3]，是国家一级重点保护植物，其树型优雅，叶片别致，其性味甘、平、涩，有小毒，具有体外抑制肿瘤细胞增殖的作用等，因此，常将其水煎剂用于治疗多种肿瘤，是中国传统观的赏树种和药用植物[4-6]。而随着苏铁的观赏价值和药用价值越来越受到人们的重视，其栽植规模越来越大，随之而来的是病害的发生越来越严重，直接影响到植株的生长，进而影响其观赏价值。目前国内对于苏铁叶枯病的研究多针对炭疽菌（Colletotrichum）和橄榄色盾壳霉（Coniothyrium olivaceum）所致的叶枯病[7-8]，拟茎点霉引起的苏铁叶枯病还未见报道。

拟茎点霉属[Phomopsis（Sacc.）Bubák.]真菌是半知菌亚门腔孢纲真菌。……