Diaporthe species occurring on citrus in China

Diaporthe species are important pathogens of a wide range of hosts including many economically important crops. Diaporthe citri is generally accepted to cause melanose of Citrus fruits, leaves and shoots; stem-end rot of fruits and gummosis of perennial branches. In this study, 147 strains of Diaporthe were isolated from diseased leaves, twigs, fruits and branches of Citrus from Shaanxi, Zhejiang, Guangxi, Fujian, Guangdong, Jiangxi, Hunan, Chongqing and Shanghai and identified by morphology and molecular analysis of nuclear ribosomal internal transcribed spacer (ITS), partial sequences of translation elongation factor 1-alpha (EF 1-alpha), tubulin (TUB) and calmodulin (CAL) genes. All strains from Citrus clustered in three clades. Diaporthe citri was the predominant species and is compared with strains from Florida, USA, where this species was first collected and described. Two new taxa differing from D. citri are described as D. citriasiana and D. citrichinensis in this paper. Inoculation tests indicate that all three species are able to cause stem-end rot of fruits, while only D. citri could cause melanose on leaves.