中国半夏主产地软腐病致病菌分离、鉴定及比较研究

Isolation,identification and comparative study of soft rot pathogens of Pinellia ternata in China

【目的】明确中国半夏主产区软腐病病原菌种类及其致病力强弱,为半夏生产和病害防控提供理论依据。【方法】对全国半夏主产区软腐病危害情况进行调查,根据柯赫氏法则对全国半夏主产区软腐病病原菌进行分离、鉴定、致病性检测以及生物学特性研究,并通过离体叶片和离体块茎回接对分离鉴定得到的3种软腐病优势病原菌进行致病力比较分析,采用抑菌圈法对3种软腐病优势致病菌进行室内药剂筛选。【结果】中国半夏软腐病主要由果胶杆菌属(Pectobacterium)的胡萝卜软腐果胶杆菌(P.carotovorum,P.aroidearum)以及狄克氏菌属(Dickeya)的D.fangzhongdai引起,其中P.carotovorum和P.aroidearum分布较广,在全国4个半夏主产区中均可检测到,而D.fangzhongdai仅存在于湖北天门半夏产区。菌株致病力强弱为P.carotovorum>D.fangzhongdai>P.aroidearum,且P.carotovorum、D.fangzhongdai和P.aroidearum更容易从半夏叶片背面进行侵染。在不同条件下培养3种软腐病菌株,结果表明最适生长温度为28~30℃,最适pH为8.0。室内药剂筛选结果表明,26种不同类型杀菌剂中化学杀菌剂噻霉酮、二氯异氰尿酸钠和植物源杀菌剂乙蒜素对3种半夏软腐病优势致病菌株有显著抑制效果,EC_(50)值均小于50μg/mL。【结论】半夏软腐病主要致病菌有P.carotovorum、P.aroidearum和D.fangzhongdai,且P.carotovorum菌株致病力最强,噻霉酮、二氯异氰尿酸钠和乙蒜素对3种半夏软腐病有显著抑制效果。

[Objective]The present paper aimed to clarify the species and the virulence of soft rot pathogens in major Pinllia ternata produc-tion areas of China,and provide technical support for P.ternata production,disease prevention and control.[Method]The disease occur-rence of soft rot was investigated in national P.ternata production areas firstly.Then,the study of isolation,identification,pathogenicity test and the biological characteristics of these soft rot pathogens were performed according to Koch's postulation.In addition,the pathogenicity of three dominant pathogens of soft rot was compared and analyzed by inoculating the leaves and tubers in vitro,and the bactericides of the three dominant pathogens were screened by using antibacterial circle measurement algorithm.[Result]P.carotovorum,P.aroidearum and D.fangzhongdai were the dominant pathogens of P.ternata in China.Among them,P.carotovorum and P.aroidearum were widely distributed and could be detected in the four major P.ternata production areas in China,while D.fangzhongdai was found only in Tianmen city of Hu-bei province.The virulence of P.carotovorum was better than D.fangzhongdai and P.aroidearum was the worst,and they were more easily to infect the P.ternata from the backside of the leaves.Culturing 3 strains in different conditions showed that the optimal growth temperature was 28-30 C and the optimal pH was 8.0.Laboratory bactericides screening experiment showed that the chemical bactericides thiamoxi-done,sodium dichloroisocyanurate and biogenic bactericide ethicallin among 26 kinds of bactericides could significantly inhibite the growth of these three dominant soft rot pathogens with the EC_(50) value of them less than 50μg/mL.[Conclusion]P.carotovorum,P.aroidearum and D.fangzhongdai were the main pathogens of soft rot of P.ternata,and P.carotovorum was the most virulent strain.Thiazolidone,sodium dichloroisonitrile and ethyl allicin had significant inhibitory effects on the three kinds of soft rot of P.ternata.