辣木枝枯病病原菌鉴定及其生物学特性

为明确海南省辣木枝枯病病原菌及其生物学特性,采用组织分离法获得菌株MO157,通过柯赫氏法则、形态学特征及分子生物学技术对该菌株进行鉴定,并测定了其菌丝生长的最佳条件。结果表明,菌株MO157回接10 d后,辣木茎干表面周围呈黄褐色,随后发病部位表现出水渍状病斑,与自然发病辣木的病状相符;菌落近圆形,菌丝初期呈白色绒毛状,后期呈浅黄色,分生孢子顶胞钩状,3~5个隔膜,厚垣孢子呈球形,在菌丝间串生;菌株MO157的ITS序列与Gen Bank中木贼镰刀菌Fusarium equiseti的相似性为100%,结合形态特征与分子鉴定最终将其确定为木贼镰刀菌(Gen Bank登陆号:KX197955)。该菌菌丝生长适宜温度25~30℃,最适温度28℃;pH 6~8时菌丝生长速率增快,pH 7时最适菌丝生长;PDA培养基和PSA培养基最适合该菌生长,以蔗糖为碳源时利用率最高;以牛肉浸膏为氮源时利用率最高;该菌致死温度为65℃,10 min;光照对菌丝生长影响较小,不同处理间菌落直径无显著差异。

Identification and biological characteristics of the pathogen causing shoot blight of Moringa oleifera

To clarify the pathogen causing shoot blight of Moringa oleifera and its biological characteristics,the strain MO 157 was obtained using the method of tissue isolation,the strain MO 157 was identified based on the Koch's postulates,morphological characteristics,molecular biological technology,and the optimum growth rate of mycelium were determined.The results showed that the water-soaked brown spots were observed on the surface of infected stems ten days after inoculation,which was similar to the symptoms and signs on stems in the field.The colonies of strain MO157 were suborbicular.The mycelium was white initially and turned yellowish later.The conidia slightly curved at apex with three to five septates,and the chlamydospore was spherical in between on mycelium.The ITS sequence of the strain MO 157 shared 100％ identity with that of Fusarium equiseti in GenBank,and the pathogen was identified as Fusarium equiseti (GenBank acc.no.KX197955).The temperature range for mycelial growth was 25-30 ℃,with the optimum temperature at 28 ℃;the mycelial growth rate increased rapidly at pH 6-8,and the optimum pH value was 7.Potato dextrose agar and potato sugar agar medium were the most suitable for mycelial growth.The utilization rates of sucrose and beef extract were the highest among all carbon and nitrogen sources,respectively.The fatal temperature for mycelial growth was 65 ℃ for 10 min.Different light conditions had little influence on the mycelium growth,and no significant differences were found in different treatments.