Recognition and characterization of four Thai xylariaceous fungi inhabiting various tropical foliages as endophytes by DNA sequences and host plant preference

A total of 202 strains of xylariaceous fungi (183 endophytic strains isolated from 25 plant species of 24 genera in 21 families and 19 saprobic strains), segregated into four clades, were examined by nuclear rDNA internal transcribed spacer (ITS) sequence and beta-tubulin coding region analyses to clarify their taxonomic status and species boundaries. Three of the four species clades were assigned to Xylaria cubensis (100 strains), Xylaria grammica (33 strains), and Nemania diffusa (48 strains). Another fungus was tentatively assigned to Nemania cf. bipapillata (21 strains). Comparison of the host plants revealed that X. cubensis inhabited healthy leaves of at least 24 plant species (23 genera of 21 families) as endophytes; N. diffusa was found on 19 plant species (18 genera of 15 families), Nemania cf. bipapillata on 11 species (10 genera of 9 families), and X. grammica on 8 species (8 genera of 7 families). The present results suggest that the major xylariaceous endophytes in tropical plants are likely to be non-host specific, or have a wide range of host plant preferences.