福建太子参黑斑病病原菌鉴定及生物学特性研究

Identification and biological characterization of the pathogen causing black spot of Pseudostellaria heterophyllain Fujian province

福建省柘荣县太子参黑斑病常于每年4—6月份的多雨季节暴发,为太子参的主要叶部病害之一,对该药材的产量和质量造成严重影响。为明确太子参黑斑病的病原菌种类及其生物学特性,该研究依据柯赫法则对病原菌分离纯化,采用形态学特征观察及多基因序列分析进行鉴定,鉴定为链格孢属致病真菌并进行致病性测定及生物学特性测定。鉴定结果表明:引起该黑斑病的病原菌为梨黑斑链格孢Alternaria gaisen。其菌落形态、孢子特征以及产孢表型特征与梨黑斑链格孢A.gaisen类似,且由ITS、tef1、gapdh、endoPG、Alta1、OPA10-2和KOG1077这7个组成的串联序列在20个链格孢属真菌的系统发育树上与梨黑斑链格孢A.gaisen聚为一支,最大似然支持率为100%,贝叶斯后验概率1.00。生物学特性表明:梨黑斑链格孢A.gaisen的菌丝生长的最适温度为25℃,最适pH为5~8,最适培养方式为24 h暗培养,菌丝和孢子致死温度均为50℃处理10 min。由A.gaisen引起的太子参黑斑病为国内外首次报道,该研究结果可为太子参叶斑类病害的诊断及防控提供理论依据。

In Zherong county,Fujian province,the black spot of Pseudostellaria heterophylla often breaks out in the rainy season from April to June every year.As one of the main leaf diseases of P.heterophylla,black spot seriously affects the yield and quality of the medicinal material.To identify and characterize the pathogens causing black spot,we isolated the pathogens,identified them as a species of Alternaria according to Koch’s postulates,and then tested their pathogenicity and biological characteristics.The results showed that the pathogens causing P.heterophyllablack spot were A.gaisen,as evidenced by the similar colony morphology,spore characteristics,sporulation phenotype,and the same clade with A.gaisen on the phylogenetic tree(the maximum likelihood support rate of 100%and the Bayesian posterior probability of 1.00)built based on the tandem sequences of ITS,tef1,gapdh,endoPG,Alta1,OPA10-2,and KOG1077.The optimum conditions for mycelial growth of the pathogen were 25℃,pH 5–8,and 24 h dark culture.The lethal conditions for mycelia and spores were both treatment at 50℃for 10 min.We reported for the first time the A.gaisen-caused black spot of P.heterophylla.The results could provide a theoretical basis for the diagnosis and control of P.heterophylla leaf spot diseases.