High diversity of Diaporthe species associated with pear shoot canker in China

Species of Diaporthe (syn. Phomopsis ) are important endophytes, saprobes and pathogens, infecting a wide range of plants and resulting in important crop diseases. However, the species occurring on pear remain largely unresolved. In this study, a total of 453 Diaporthe isolates were obtained from branches of Pyrus plants (including P. bretschneideri , P. communis , P. pyrifolia and P. ussuriensis collected from 12 provinces in China) showing shoot canker symptoms. Phylogenetic analyses based on five loci (ITS, TEF , CAL , HIS , and TUB ) coupled with morphology of 113 representative isolates revealed that 19 Diaporthe species were isolated, representing 13 known species (including D. caryae , D. cercidis , D. citrichinensis , D. eres , D. fusicola , D. ganjae , D. hongkongensis , D. padina , D. pescicola , D. sojae , D. taoicola , D. unshiuensis and D. velutina ) and six new species described here as D. acuta , D. chongqingensis , D. fulvicolor , D. parvae , D. spinosa and D. zaobaisu . Although Koch's postulates confirmed all species to be pathogenic, a high degree of variation in aggressiveness was observed. Moreover, these species have a high diversity, plasticity, and prevalence related to the geographical location and pear species involved.