茶叶斑病病原菌的鉴定及生长特性研究

Identification and Growth Characteristics of Tea Leaf Spot Pathogenic

本研究从贵州余庆茶叶产区的茶树叶部病害样品中分离纯化出多个相似的分离物,观察其菌落、分生孢子器和分生孢子等形态。测定了LSU、ITS和TUB等核酸序列,采用PAUP软件及最大简约法,进行多基因系统发育树分析。依据柯赫氏法则,完成代表性菌株CGMCC3.20149在室内和自然条件下的茶树叶片致病性研究。同时,还探究了菌株CGMCC3.20149在不同培养基上的生长速率。结果表明,CGMCC3.20149菌株的菌落、分生孢子器和分生孢子等形态与荸荠点霉秆枯病菌Didymella bellidis一致;CGMCC3.20149菌株与模式菌株D.bellidis PD 94/886和D.bellidis CBS 714.85在系统发育树上聚为一支,自举支持率为100%;通过损伤方式接种,CGMCC3.20149菌株可引起茶树叶片产生病斑;在OA培养基上的生长速率最快,达(0.76±0.01)cm/d,PDA培养基上的生长速率次之,为(0.73±0.02)cm/d,MEA培养基上的生长速率则最慢,为(0.62±0.01)cm/d;不同的碳素营养和氮素营养均影响菌丝的生长速率、菌素丰度、色素形成;25℃是菌株体外最适宜的生长温度;菌株在pH 6~9的范围内生长较好。

Tea leaf spot has been a significant disease in tea plantations in Yuqing County,Guizhou Province.To effectively control the occurrence and damage of tea leaf spot in this region,we isolated and purified many isolates from the tea leaf disease samples with similar morphology,then observed the morphologies of the colonies,pycnidia,and conidia.The phylogenetic analysis was conducted by PAUP software with the method of Maximum parsimony by multi-locus sequences of LSU,ITS,and TUB genes.According to Koch’s rule,the representative strain CGMCC3.20149 was conducted the pathogenicity test for tea leaves under laboratory condition and natural condition.Meanwhile,the growth of the strain CGMCC3.20149 was also studied under different mediums.The results indicated that the morphologies of the strain CGMCC3.20149 were similar to that Didymella bellidis at the colonies,pycnidia,and conidia.The strain CGMCC3.20149 was identical to the reference isolates D.bellidis PD 94/886 and D.bellidis CBS 714.85,and the clade was supported by 100%bootstrap values.The growth characteristics of strain CGMCC3.20149 on PDA,OA,and MEA medium showed that the fastest growth rate was(0.76±0.01)cm/d in the OA medium,followed by(0.73±0.02)cm/d on PDA medium,and the slowest growth rate was(0.62±0.01)cm/d on MEA medium.Different carbon and nitrogen nutrition could influence the growth of hypha,the abundance of hyphae,and the formation of pigment.The optimal condition for the highest growth velocity was 25 oC,the strain could adapt to pH of 6~9.