重庆樟树溃疡病病原菌的鉴定及序列分析

目的 为了明确重庆樟树溃疡病的病原菌种类。 方法 采集重庆市渝中区、北碚区和涪陵区的樟树溃疡病样品进行病原菌的分离与纯化，观察病原菌的形态学特征，对不同菌落形态代表菌株的rDNA-ITS、β-tubulin和EF1-α序列进行扩增和测序，构建系统进化树，并测定其致病性。 结果 从重庆不同地区采集的樟树溃疡病样品中共分离得到48份菌株，单菌丝纯化后得到68株纯化菌株，根据纯化菌株在PDA培养基上的培养特性及分生孢子特征，将其分为Ⅰ型、Ⅱ型和Ⅲ型3种类型。选取不同类型的代表菌株构建系统进化树，结果表明：这3类菌株分别为葡萄座腔菌属中的Botryosphaeria dothidea、B.parva和B.rhodina。致病性测定结果发现：所有菌株均能使樟树枝条产生黑色坏死病斑，且B.parva菌株的致病性最强，B.rhodina菌株的致病性次之，B.dothidea菌株的致病性最弱。 结论 重庆樟树溃疡病的病原菌为B.dothidea、B.parva和B.rhodina，其中B.rhodina和B.parva为引起樟树溃疡病的首次报道。

Identification and Sequence Analysis of Canker Pathogen of Camphor Tree in Chongqing

Objective To identify the pathogen of camphor tree (Cinnamomum camphora) canker disease, the diseased branches of camphor tree were collected from the Fuling, Beibei and Yuzhong district of Chongqing. Method Pathogens were isolated from the diseased samples and purified by single-mycelium tips culture. The species of pathogens were primarily identified by the morphological characterizations of purified strains. To analyze the phylogenetic of the selected strains, the sequences of rDNA-ITS, β-tubulin and EF1-α genes were amplified and sequenced. The selected strains showing different morphological and molecular characteristics were tested for their pathogenicity on detached shoots of camphor. Result A total of 48 isolates were isolated from the diseased camphor tree canker samples in Chongqing, and 68 purified strains were obtained by single-mycelium tip technique. Based on the characterization of fungal colony and conidia, the 68 purified strains were grouped into three types. Fourteen strains from the three types were selected to construct phylogenetic tree. The phylogenetic analysis results showed that the three types belong to Botryosphaeria dothidea (type Ⅰ), B. parva (type Ⅱ) and B. rhodina (type Ⅲ). Pathogenicity tests on the camphor tree shoots showed that all the tested strains could induce canker lesions. Remarkably, the strains of B. parva exhibited the strongest virulence than that of the B. rhodina and B. dothidea strains. The B. dothidea strains showed the weakest virulence. Conclusion B. parva, and B. rhodina are isolated from camphor canker disease for the first time. It is suggested that B. dothidea, B. parva, and B. rhodina are the common causal agents for camphor tree canker diseases in Chongqing.