红叶石楠叶斑病致病菌的分离与鉴定

Isolation and identification of pathogenic fungus of Photinia×fraseri leaf spot disease

【目的】为明确红叶石楠患叶斑病叶片的致病菌,以期为红叶石楠叶斑病的防控提供借鉴参考。【方法】2022年9月以福建省南平市武夷山市武夷学院采集的患病叶片为材料,利用传统微生物培养法分离纯化致病菌,进行柯赫氏法则验证,通过形态学鉴定和ITS序列分析明确致病菌的种类。【结果】从病叶中分离得到的菌株a在PDA培养基上呈白色絮状,有明显的轮纹,分生孢子为纺锤形,菌株a的ITS序列与NCBI数据库中小孢拟盘多毛孢属(Pestalotiopsis microspora,登录号:AY924271.1)的相似性为99%。菌株b在PDA培养基上呈白色蓬松状,有大量气生菌丝,孢子呈黑色球状,菌株b的ITS序列与NCBI数据库中稻黑孢属(Nigrospora oryzae,登录号:KT192348.1)的相似性为99%。接种菌株a和菌株b均能使离体叶片发病,且症状与供试叶片的症状相似。【结论】引发武夷学院红叶石楠叶斑病的病原物为小孢拟盘多毛孢菌和稻黑孢菌。

[Objective]This study was conducted to identify the pathogenic microorganism responsible for leaf spot diseases on the leaves of Photinia×fraseri,providing a reference for the prevention and controling of such diseases of this landscape plant.[Method]The diseased leaves collected from Wuyishan,Nanping,Fujian Province,in September 2022,were used as materials.The pathogenic fungus was isolated and purified by using the traditional microbiological culture method.Koch's postulates were then used to verify the experimental results,and the pathogenic fungus was identified through the morphological identification and ITS sequence analysis.[Result]Strain a,isolated from diseased leaves,exhibited white cotton-like growth and distinct concentric rings on PDA medium,with spindle-shaped conidia.The ITS sequence of the strain a shared 99%similarity with that of Pestalotiopsis microspora(accession No.AY924271.1)in the NCBI database.Strain b displayed white fluffy growth with abundant aerial mycelium and black spherical spores on PDA medium.The ITS sequence of strain b shared 99%similarity with that of Nigrospora oryzae(accession No.KT192348.1)in the NCBI database.Upon inoculation with both strains a and b,symptoms similar to those observed on the initially collected diseased leaves were induced.[Conclusion]Therefore,both P.microspora and N.oryzae were identified as responsible for the leaf spot diseases on P.fraseri in Wuyi University.