Diaporthe from walnut tree (Juglans regia) in China, with insight of the Diaporthe eres complex

Species of Diaporthe are important plant pathogenic fungi that commonly occur on a wide range of hosts. They are relatively difficult to identify due to their extreme similarity in morphology and confusing multigene phylogeny, especially in the Diaporthe eres complex. In the present study, isolates were collected from diseased branches of Juglans regia in China. Most strains were clustered into the D. eres species complex based on the combined internal transcribed spacer (ITS) region, partial calmodulin (CAL), histone H3 (HIS), translation elongation factor 1-alpha (TEF1-alpha) and beta-tubulin (TUB) genes. To focus on this complex, CAL, TEF1-alpha and TUB were selected in further phylogenetic analyses that showed a better topology compared with combined five-gene phylogeny. Results revealed that all strains which clustered in the Diaporthe eres complex from Juglans regia in China were Diaporthe eres. Results suggested a revised species criterion in the Diaporthe eres complex. The current study uncovered a new species here described as Diaporthe. tibetensis.