一株地黄叶枯病致病菌的鉴定及生物学特性研究

Identification and biological characteristics of a pathogen causing leaf blight of Rehmannia glutinosa

2019年在河南省温县地黄种植园发现一种地黄叶枯病。采集具有褐色病斑症状的地黄植株,从叶部感病部位分离、纯化出3株病原菌。通过对病原菌致病性测定、形态学典型特征观察以及ITS、EF1-α、Tub多基因序列分析,鉴定出3株病原菌,分别为层出镰刀菌Fusarium proliferatum、尖孢镰刀菌F.oxysporum和锐顶镰刀菌F.acuminatum,其中锐顶镰刀菌F.acuminatum尚未见有侵染地黄的报道,是地黄叶部病害的新型致病菌。为明确锐顶镰刀菌F.acuminatum的生物学特性,测定了光照、pH、温度、培养基、碳源和氮源在5 d的培养期内对病原菌菌丝生长速率的影响,并探究了菌丝生长的致死温度。研究结果表明,锐顶镰刀菌F.acuminatum菌丝在12 h光照/12 h黑暗条件下生长最好;在5~40℃均可生长,最适生长温度为25℃;在pH 4~11均可生长,最适生长pH 7.0;在多种培养基上均可生长,其中燕麦琼脂培养基上生长最快;对多种碳氮源均可利用,其中利用率最高碳源为可溶性淀粉,利用率最高氮源为硝酸钠;菌丝致死温度51℃,10 min。该研究结果可为锐顶镰刀菌F.acuminatum引起的地黄病害田间诊断和防治提供科学依据。

Leaf blight outbroke in Rehmannia glutinosa plantation in Wenxian county, Henan province in 2019. R. glutinosa plants with diseased leaves were collected from the plantation, and three strains were isolated from the diseased leaf samples. Pathogenicity test, morphological observation, and phylogenetic analysis of ITS, EF1-α, and Tub suggested that they were respectively Fusarium proliferatum, F. oxysporum, and F.acuminatum. Among them, F. acuminatum, as a pathogen of R. glutinosa leaf disease, had never been reported. To clarify the biological characteristics of F. acuminatum, this study tested the influence of light, pH, temperature, medium, carbon source, and nitrogen source on the mycelial growth rate of the pathogen during a 5-day culture period, and explored the lethal temperature. The results showed that the mycelia grew well under the photoperiod of 12 h light/12 h darkness, at 5-40 ℃(optimal temperature: 25 ℃), at pH 4-11(optimal pH: 7.0), on a variety of media(optimal medium: oatmeal agar), and in the presence of diverse carbon and nitrogen sources(optimal carbon source: soluble starch;optimal nitrogen source: sodium nitrate). The lethal temperature was verified to be 51 ℃(10 min). The conclusion is expected to lay a scientific basis for diagnosis and control of R. glutinosa leaf diseases caused by F. acuminatum.