Diversity and Pathogenicity of Six Diaporthe Species from Juglans regia in China.

Walnut ( Juglans regia L.) is cultivated extensively in China for its substantial economic potential as a woody oil species. However, many diseases caused by Diaporthe greatly affect the health of Juglans regia trees. The present study revealed the presence of Diaporthe species from Juglans regia . A total of six species of Diaporthe were isolated from twigs of Juglans regia in three provinces in China, including two known species ( Diaporthe gammata and D. tibetensis ) and four novel species ( D. chaotianensis , D. olivacea , D. shangluoensis and D. shangrilaensis ). Phylogenetic relationships of the new species were determined by multilocus phylogenetic analyses based on partial sequences of the internal transcribed spacer (ITS) region, calmodulin ( cal ) gene, histone H3 ( his3 ) gene, translation elongation factor 1-α ( tef1-α ) gene and β-tubulin ( tub2 ) gene. Pathogenicity tests indicated that all Diaporthe species obtained in this study were confirmed as pathogens of Juglans regia . This study deepens the understanding of species associated with several disease symptoms in Juglans regia and provides useful information for effective disease control.