First Report of Botryosphaeria dothidea Causing Sweet Osmanthus Leaf Dieback in China

Sweet osmanthus is one of the ten traditional famous flowers in China. The occurrence of the diseases caused by fungi other than Botryosphaeria spp. has been reported mainly from China on sweet osmanthus. A leaf dieback of sweet osmanthus caused by Botryosphaeria sp. was found for the first time in 2007 in Nanning City, Guangxi, China. The objectives of the present study were to isolate and characterize the causal organism of sweet osmanthus leaf dieback. The fungus was isolated from the lesions of affected sweet osmanthus leaves and its pathogenicity to sweet osmanthus was confirmed using a detached-leaf-inoculation method. The identification of the pathogen was carried out mainly based on the morphological characters and molecular analysis of internal transcribed spacer (ITS) sequences. The morphological characters of the pathogenic isolate GHX6 were agreed with that of Botryosphaeria dothidea. The ITS sequence of the isolate was amplified with primers ITS1 and ITS4, and submitted to GenBank (accession no. GQ368251). Molecular analysis based on ITS sequence comparison between the isolate GHX6 and the other related fungi derived from GenBank supported that the causal agent of the sweet osmanthus leaf dieback belonged to Botryosphaeria dothidea. This is the first report of Botryosphaeria dothidea causing leaf dieback on sweet osmanthus in China.