桉树焦枯病菌产毒条件优化及毒素专化性测定

Optimal culture conditions for Calonectria pseudoreteaudii crude toxin production,and host specificity of the toxin

桉树焦枯病菌是桉树焦枯病的致病菌,为明确该菌的致病因子及致病机制,对YA5j2菌株的最佳产毒条件及毒素专化性进行了研究,采用离体叶片针刺法对致病菌毒素进行生物活性测定。结果表明,桉树焦枯病菌产生的毒素对桉树叶片有毒性,叶片病斑面积与粗毒素的浓度成正相关关系。YA5j2菌株的最佳产毒条件:培养基为改良Fries′培养基,培养温度为28℃,pH值为5,并在黑暗条件下连续振荡培养15~20 d,转速为150 r·min-1。专化性测定结果表现出多样性,显示该粗毒素属于非寄主专化性毒素,可以用来区分植物抗病性的强度。21种供试植物经粗毒素处理后,小叶榕、白兰、樟树、桂花等植物对毒素的病理反应最强,将来可作为快速评价毒素的生测材料。

Eucalyptus,as one of important economic tree species,was cultivated worldwide including China.It is of importance to investigate the pathogenesis of Calonectria pseudoreteaudii,a leaf blight pathogen,and the role of its toxin in the pathogenic process.The present study evaluated the optimal culture conditions for toxin production by Calonectria pseudoreteaudii YA5j2 as well as the host specificity of the toxin.Bioactivity assay results indicated that the toxin affected eucalyptus leaves.The lesion area on the leaves had a positive correlation with toxin concentration.The optimal culture conditions for toxin production by Calonectria pseudoreteaudii YA5j2 were observed in a modified Fries′medium at 28℃and a pH of 5,with a culture period of 15-20 days while being rotated at 150 r·min-1.The culture was also subjected to constant shaking and darkness.A toxicity bioassay indicated that the Calonectria pseudoreteaudii YA5j2 toxin was a non-host specific toxin.The results of the toxicity bioassay conducted on 21 plants demonstrated that the toxin had high toxicity to Ficus concinna,Michelia alba,Cinnamomum camphora,and Osmanthus fragrans.