山核桃干腐病病原菌的鉴定

Identification of the pathogens causing stem canker on Carya cathayensis

葡萄座腔菌科Botryosphaeriaceae真菌是很多木本植物溃疡病和枯梢病的重要病原菌。已有报道认为:山核桃干腐病病原菌为茶藨子葡萄座腔菌Botryosphaeria dothidea,但对于葡萄座腔菌科其他真菌与山核桃干腐病的关系还没有深入研究。分离得到了山核桃干腐病相关病原菌,通过比较其形态学特征和核糖体DNA内转录间隔区(rDNA ITS)序列特征,将分离得到的供试菌株分为3组。根据形态学特征和基于ITS序列的系统发育分析,3组菌株分别鉴定为Botryosphaeria dothidea,B.fabicercianum和B.obtusa。其中B.dothidea为优势菌株,分离频率为71.42%,B.fabicercianum和B.obtusa分离频率分别为14.28%。经致病性测定,上述分离菌株均能引起健康山核桃Carya cathayensis枝条发病,但致病性存在差异。在山核桃上发现的B.obtusa和B.fabicercianum为首次报道。

Species of the Botryosphaeriaceae family are important pathogens causing cankers and die-back on many woody plants. In previous studies Botryosphaeria dothidea has commonly been reported as a pathogen of Chinese hickory （Carya cathayensis ） canker; however, it was unclear whether other species of Botryosphaeri- aceae were also related to hickory canker. In one study, several species of Botryosphaeriaceae were isolated from Chinese hickory, and then they were identified based on anamorphic morphology and rDNA Internal Tran- scribed Spacer （ITS） sequences. A phylogentic analysis indicated that these isolates formed three clades and were identified as B. dothidea, B. fabicercianum, and B. obtusa with isolation rates of B. dothidea （71.42%） predominant and B. fabicercianum and B. obtusa being much lower （14.28%）. In pathogenicity testing, all three pathogens caused stem cankers on Chinese hickory but had different degrees of pathogenicity. B. obtusa and B. fabicercianum were first reported as a pathogen of Carya cathayensis canker.