湖南省油茶炭疽病病原鉴定

摘要

[目的]研究湖南省油茶炭疽病病原,为该病害的防控提供依据.[方法]采集湖南省长沙、株洲、浏阳、永州、怀化、常德、常宁等油茶主产区9个样地的典型油茶炭疽病叶,分离纯化叶片病健交界处的真菌菌株,观察菌株在(PDA)培养基上的菌落、分生孢子及附着孢的形态特征,确定为炭疽属真菌.进一步对炭疽属菌株进行柯赫氏法则验证,确定油茶炭疽病病原菌菌株.对获得病原菌的 rDNA-ITS、CAL 和 GAPDH 3个基因进行 PCR 扩增和测序,得到的基因序列与 GenBank 中已有模式炭疽属菌株序列按照3个基因一致的顺序拼接后采用 PAUP 和MrBayes 软件构建系统发育树.[结果]从湖南省9个采样地共分离获得62株炭疽属菌株,致病性测试表明这62株菌均能对油茶嫩叶和果致病,但不同菌株的发病时间具有一定差异;根据形态特征及多基因系统发育分析,最终明确湖南省油茶炭疽病的病原种类.[结论]湖南省油茶炭疽病的病原菌包含果生炭疽菌、暹罗炭疽菌、胶孢炭疽菌、山茶炭疽菌和哈锐炭疽菌5种炭疽属真菌,其中果生炭疽菌分布范围最广,分离率最高,达到64.5%.%[Objective]The filamentous fungi,Colletotrichum spp.,are found in all five continents and are capable of causing severe diseases in the important plants such as Camellia oleifera (oil-tea trees). The pathogen causes defoliation, as well as necrotic spots on fruits. In recent years,the disease is rapidly spreading in the oil-tea trees producing areas of southern China. The objective of this study is to identify the pathogen causing stem and leaf anthracnose on oil-tea trees in Hunan,and to provide a basis for disease control and resistance breeding. [Method]Infected leaves were collected from Changsha,Zhuzhou,Liuyang,Yongzhou,Huaihua,Changde and Changning City,in Hunan Province and the fungi were isolated and purified from the diseased border of leaves on acidified potato dextrose agar(PDA) plate. Identification of the pathogen was based on morphology of colony and conidial,pathogenicity tests. Isolates were characterized by colony morphology,conidial characteristics under 28 ℃ in dark. The rDNA-ITS,CAL and GAPDH region of isolates were amplified and sequenced. PAUP and MrBayes software were used to analyze the data of ITS-CAL-GAPDH sequences.[Result]The result showed that a total of 62 colletotrichum strains were isolated from oil tea plants in 9 oil-tea plantations of Hunan provinces. Pathogenicity test showed that all of the isolates could infect oil-tea leaves and fruit,with different time in the onset of disease symptom. The multilocus sequence analysis,together with a critical examination of the phenotypic characters,revealed five previously described species. [Conclusion]The typical anthracnose symptoms of oil-tea leaves in Hunan Province were described in this study. Based on the morphology and multiple gene sequences characters,the 62 isolates were identified as C. fructicola,C. siamense,C. gloeosporioides,C. horii and C. camelliae. Among them,C. fructicola had the highest isolated rate that was accounted for 64.5%.