Endophytic Diaporthe associated with Citrus: A phylogenetic reassessment with seven new species from China

Phytopathogenic species of Diaporthe are associated with melanose, stem-end rot and gummosis diseases of Citrus. However, little is known about the occurrence of species of Diaporthe as endophytes and saprobes. In this study, we obtained 58 strains of Diaporthe, including 44 endophytic isolates from cultivated Citrus in China. The nuclear ribosomal internal transcribed spacer (ITS), partial sequences of translation elongation factor 1-α (EF1-α), beta-tubulin (TUB), and histone-3 (HIS) gene regions were analysed to determine the species of the isolates collected. In combined analysis of four gene regions, these strains grouped in 16 distinct clades in Diaporthe. The isolates were identified in Diaporthe arecae species complex, Diaporthe citri, Diaporthe citriasiana, Diaporthe citrichinensis, Diaporthe endophytica, Diaporthe eres, Diaporthe hongkongensis, and Diaporthe sojae based on molecular phylogeny and morphology. Seven new species are described from Citrus namely, Diaporthe biconispora, Diaporthe biguttulata, Diaporthe discoidispora, Diaporthe multigutullata, Diaporthe ovalispora, Diaporthe subclavata, and Diaporthe unshiuensis with descriptions and illustrations.