福建省鲜食玉米小型叶斑病的病原菌鉴定

鲜食玉米是福建省重要的经济作物。由丝状真菌引起的玉米叶斑病是玉米生产上的重要病害,严重影响了玉米的产量和品质。明确叶斑病的病原菌种类,可以为鲜食玉米病害的综合防控提供理论依据。本研究采用组织分离法对福州、莆田、漳州、南平和宁德5个地区采集的玉米病叶上典型的小型病斑(病斑长度5mm)进行病菌分离和纯化,结果共获得103株单孢分离菌株。初步形态学观察后选取其中的8株代表性菌株进行鉴定,发现有5个菌株的形态特征与玉米小斑病菌的形态特征相似;而另3个菌株的形态特征与玉米弯孢叶斑病菌的形态特征极其相似。8个菌株接种感病玉米品种后出现了与田间相似的叶斑病症状。rDNA-ITS序列分析结果表明,8个供试菌株中有5个菌株鉴定为玉米小斑病菌Bipolaris maydis,2个菌株为玉米新月弯孢叶斑病菌Curvularia lunata,1个菌株为画眉草弯孢叶斑病菌Curvularia eragrostidis。上述研究结果表明,引起福建省鲜食玉米叶斑病的病原菌为B.maydis、C.lunata和C.eragrostidis。其中C.eragrostidis引起玉米叶斑病在福建省属首次报道。毒力测定结果表明,供试的8个菌株对8个不同玉米品种的毒力表现出多样性。

Pathogen Identification of Small Leaf Spots on Sweet Corn Plants in Fujian

Sweet corn (Zea mays L.) is one of the most important economic crops in Fujian Province.The small leaf spots on the leaves from filamentous fungal infection significantly affect the yield and quality of the corn.To identify the pathogenic agents that caused the disease on sweet corns is essential for the disease control and prevention.Using the single-spore isolation methodology,103 fungal species were obtained from the corn leaves showing typical small spots (lesion length ＜ 5 mm) in Fuzhou,Putian,Zhangzhou,Nanping and Ningde,where the major corngrowing regions in Fujian are located.After a preliminary morphological observation,8 representative isolates were selected for further examinations.Among them,5 were morphologically identical to Bipolaris maydis,and 3 highly resembled Curvularia spp.A pathogenic assay on all plants inoculated with the pathogens exhibited similar symptoms as observed on the diseased corns in the field.The rDNA-ITS sequences of 5 isolates were subsequently identified as B.maydis,two as C.lunata,and one as C.eragrostidis.It suggested that the microorganisms that caused the small leaf spots on sweet corns in Fujian were any of those identified.For Fujian,to report C.eragrostidis as culprit of the disease was the first time in China.The degrees of virulence of the 8 identified isolates varied significantly toward 8 different corn varieties.