Short CommuniCation CHARACTERIZATION OF ALTERNARIA SPECIES ASSOCIATED WITH WATERMELON LEAF BLIGHT IN BEIJING MUNICIPALITY OF CHINA

Leaf blight symptoms consisting of dark brown lesions were observed on watermelon plants in seven districts or counties in Beijing municipality of China. A total of 64 Alternaria isolates were recovered and identified based on morphological characters and sequence analyses of rDNAITS regions and histone 3 genes. Amongst these isolates, Alternaria tenuissima was the most prevalent species representing 76.6% of the isolates, followed by A. alternata (23.4%). All isolates were divided into individual clades representing two species, A. tenuissima and A. alternata, according to phylogenetic analysis of histone 3 gene. Representative Alternaria isolates of the two species induced dark brown lesions on detached watermelon leaves, with disease incidence ranging from 44.4-83.3%. These results allowed the identification of the presence of Alternaria populations causing watermelon leaf blight for the first time in Beijing municipality of China.