Anthracnose fungi with curved conidia, Colletotrichum spp. Belonging to ribosomal groups 9-13, and their host ranges in Japan

Abstract

Ninety fungal strains with falcate conidia belonging to Colletotrichum spp. classified into the ribosomal groups 9-13 (the RG 9-13 spp.) and preserved at the NIAS Genebank, Japan were re-identified based on molecular phylogenetic analysis of the internal transcribed spacer (ITS) region of the rRNA gene, sequences of the glyceraldehyde 3-phosphate dehydrogenase, chitin synthase 1, histone3, and actin genes, and partial sequences of β-tubulin-2 (TUB2) genes, or by BLASTN searches with TUB2 gene sequences. Seventy strains were reclassified into nine recently revised species, C. chlorophyti, C. circinans, C. dematium sensu stricto, C. lineola, C. liriopes, C. spaethianum, C. tofieldiae, C. trichellum and C. truncatum, whereas 20 strains were grouped into four unidentified species. RG 9, 10 and 12 corresponded to the C. spaethianum, C. dematium and C. truncatum species complex, respectively, while RG 11 and 13 agreed with C. chlorophyti and C. trichellum, respectively. Phylograms derived from a six-locus analysis and from TUB2 single-locus analysis were very similar to one another with the exception of the association between C. dematium s. str. and C. lineola. Thus, TUB2 partial gene sequences are proposed as an effective genetic marker to differentiate species of RG 9-13 in Japan except for C. dematium s. str. and C. lineola. Thirty-two plant species were identified as new hosts for seven of the species found in this study except for C. circinans and C. trichellum; and two unidentified species. Colletotrichum chlorophyti, C. lineola, C. liriopes, C. spaethianum, and C. truncatum were regarded as polyphagous, whereas C. trichellum and Colletotrichum sp. (Ra), designated tentatively in this study, appeared to have specific pathogenicity to single hosts, Hedera rhombea and Raphanus sativus var. hortensis, respectively. Conidial curvature properties, "outer curvature," "inner curvature" and "height/width ratio" successfully represented conidial shape parameters. Conidial curvature properties of the species in RG 9, 10 and 12 were found to correlate with the species complexes.