桉树溃疡病病原菌的鉴定

 随着桉树人工纯林的面积扩大，桉树病害也日趋加重，严重影响和制约桉树产业的发展。2008年至今，在云南省石林县和红河州桉树种植区发生一种病害，主要为害嫩枝、枝条和主干，发病初期，感病枝条和主干上产生红褐色圆或椭圆形坏死斑，以后逐渐扩大成椭圆或不规则溃疡斑，病变扩展到木质部后，常造成枝条生长畸形，易引起刮风断裂。主干树皮下明显呈黑褐色坏死，并造成感染面周围树皮开裂，溃疡处一般可看到流胶，严重时造成整株干枯死亡。调查发现，该病发病率通常在 10％～25％，重者可达 40％ 以上，引起桉树溃疡和枯萎死亡。本文通过病原菌分离、致病性测定及传统、分子鉴定明确了该病的病原，以期为病害防治提供理论依据。

Identification of the pathogen causing canker in eucalyptus

The identification of the pathogens isolated from the canker of eucalyptus (Eucalyptus grandis) were carried out. Seventeen diseased eucalyptus samples were observed in Shilin and Honghe in Yunnan Province (south-western China). Seventeen isolates of possible pathogenic fungi were isolated from trunks and branches of infected eucalyptus plants. Bases on the pathogenicity experiment, the results showed that YNE1-YNE17 were the pathogens of eucalyptus (E.grandis) canker disease. The morphological identification showed that YNE1-YNE17 was identified as Botryosphaeria dothidea．By analysis of the rDNA internal transcribed spacer region (ITS1-5.8S-ITS2). BLAST searches at GenBank showed a high identity with reference sequences (99%-100%). Representative sequences of both regions were deposited to GenBank (Accession No. FJ517657, FJ517658). Morphological and molecular identification confirmed this species as B. dothidea. B. dothidea was first reported as the pathogen of eucalyptus canker and shoot blight disease in China.