一种油茶新炭疽病原的多基因系统发育分析鉴定

Pathogen identification of a new anthracnose of Camellia oleifera in China based on multiple-gene phylogeny

为明确我国油茶炭疽病病原菌的种类,对采集自我国6个省市油茶产区的炭疽病样本进行病原菌分离,通过形态学特征并结合多基因谱系分析方法构建系统发育树进行比较分析。结果表明共分离到能引起油茶叶出现炭疽病症状的病原菌23株。病原菌在PDA培养基上28℃培养7 d后,菌落圆形,初期白色,逐渐变为灰色,最终为灰黑色;分生孢子堆橘黄色,分生孢子椭圆形、单胞、无色,大小为(16.8±0.7)μm×(5.7±0.4)μm;菌丝附着孢椭圆形,褐色,边缘光滑、完整,大小为(9.5±1.5)μm×(6.1±0.6)μm。多基因系统发育树显示,这23株病原菌与包括模式菌株ICMP18581在内的所有果生刺盘孢菌Colletotrichum fructicola菌株序列聚为一个进化枝,置信度高达100%。根据形态特征及多基因系统发育树,鉴定这23株病原菌为果生刺盘孢菌C.fructicola,为国内油茶上果生刺盘孢菌的首次报道。

In order to identify the infectious pathogen to the species level, samples of diseased Colletotrichum fructicola leaves with the anthracnose syndrome were collected from six provinces in China.A total of 23 isolates were obtained. Their colonies on PDA were colorless at first,and then turned grey and grey-black seven days after incubation at 28 ℃. The conidial spore aggregate appeared orange while individual conidium was oblong,single-celled,and colorless,and( 16. 8 ± 0. 7) μm ×( 5. 7 ± 0. 4) μm in size. Appressoria from mycelia were ellipse,brown,smooth,and( 9. 5 ± 1. 5) μm ×( 6. 1 ± 0. 6) μm in size. Multiple-gene phylogenetic analyses indicated that these 23 isolates were grouped in the same clade as Colletotrichum fructicola,with a bootstrap support of 100%. This is the first report that C. fructicola is the major causal agent of C. oleifera anthracnose in China.