Unravelling Diaporthe Species Associated with Woody Hosts from Karst Formations (Guizhou) in China

Abstract

Though several Diaporthe species have been reported in China, little is known about the species associated with nature reserves in Guizhou province. During a survey of fungi in six nature reserves in Guizhou province of China, thirty-one Diaporthe isolates were collected from different woody hosts. Based on morphology, culture characteristics and molecular phylogenetic analysis, these isolates were characterized and identified. Phylogenetic analysis of internal transcribed spacer region (ITS), combined with translation elongation factor 1-alpha (tef), β-tubulin (tub), calmodulin (cal) and histone H3 (his) gene regions identified five known Diaporthe species and seven distinct lineages representing novel Diaporthe species. The details of five known species: Diaporthe cercidis, D. cinnamomi, D. conica, D. nobilis and D. sackstonii are given and the seven new species D. constrictospora, D. ellipsospora, D. guttulata, D. irregularis, D. lenispora, D. minima, and D. minusculata are introduced with detailed descriptions and illustrations. This study revealed a high diversity of previously undescribed Diaporthe species associated with woody hosts in various nature reserves of Guizhou province, indicating that there is a potential of Diaporthe species remains to be discovered in this unique landform (Karst formations) in China. Interestingly, the five known Diaporthe species have been reported as pathogens of various hosts, and this could indicate that those newly introduced species in this study could be potentially pathogenic pending further studies to confirm.

Keywords: Diaporthaceae; asexual morph; phylogeny; seven new taxa; taxonomy.

Figure 1

Phylogram generated from maximum likelihood analysis of Diaporthe species isolated in this study and their phylogenetically closely related species based on combined internal transcribed spacer region (ITS), tef, tub, cal and his sequence data. Bootstrap support values for ML ≥ 70%, MP ≥ 70%, are indicated above the nodes and the branches are in bold indicate Bayesian posterior probabilities ≥0.9. The tree is rooted with Diaporthella corylina (CBS 121124). Isolate numbers of ex-types and reference strains are in bold. Taxa isolated in this study are in blue.

Figure 1

Phylogram generated from maximum likelihood analysis of Diaporthe species isolated in this study and their phylogenetically closely related species based on combined internal transcribed spacer region (ITS), tef, tub, cal and his sequence data. Bootstrap support values for ML ≥ 70%, MP ≥ 70%, are indicated above the nodes and the branches are in bold indicate Bayesian posterior probabilities ≥0.9. The tree is rooted with Diaporthella corylina (CBS 121124). Isolate numbers of ex-types and reference strains are in bold. Taxa isolated in this study are in blue.

Figure 2

Diaporthe constrictospora (HKAS 107534, holotype). (a,b) Ascomata on host surface. (c,d) Section ofascomata (e) 10 days old culture on potato dextrose agar (-) from above. (f) 10 days old culture on PDA from reverse. (g–j) Asci. (k,l) Ascospores. (m) Germinating ascospore. Scale bars: (c,d) = 100 μm, (g–m) = 10 μm.

Figure 3

Diaporthe ellipsospora (HKAS 107535, holotype). (a,b) Ascomata on host surface. (c) Section of an ascoma. (d) 8 days old culture on PDA from above. (e) 8 days old culture on PDA from reverse. (f) Immature ascus. (g–k) Mature asci. (l–p) Ascospores. (q) Paraphyses. Scale bars: (c) = 100 μm, (f–k) = 10 μm, (l–q) = 5 μm.

Figure 4

Diaporthe guttulata (HKAS 107536, holotype). (a,b) Ascomata on host surface. (c) Section of an ascoma. (d) 7 days old culture on PDA from above. (e) 7 days old culture on PDA from reverse. (f) Immature ascus. (g–j) Mature asci. (k,l) Ascospores. Scale bars: (c) = 100 μm, (f–l) = 10 μm.

Figure 5

Diaporthe irregularis (HKAS 107537, holotype). (a,b) Ascomata on host surface. (c) 10 days old culture on PDA from above. (d) 10 days old culture on PDA from reverse. (e) Immature ascus. (f,g) Mature asci. (h,i) Ascospores. Scale bars: (e–g) = 10 μm, (h,i) = 5 μm.

Figure 6

Diaporthe lenispora (HKAS 107538, holotype). (a,b) Ascomata on host surface. (c) Ostiole. (d,e) Section of ascomata. (f) Immature ascus. (g–i) Mature asci. (j,k) Ascospores. (l) 10 days old culture on PDA from above. (m) 10 days old culture on PDA from reverse. Scale bars: (c) = 100 μm, (d,e) = 50 μm, (f–j) = 10 μm, (k) = 5 μm.

Figure 7

Diaporthe minima (HKAS 107539, holotype). (a,b) Conidiomata on host surface. (c,d) Section of conidiomata. (e,f) Alpha conidia attached to conidiogenous cells. (g) Alpha conidia. Scale bars: (c,d) = 50 μm, (e–g) = 10 μm.

Figure 8

Diaporthe minusculata (HKAS 107540, holotype). (a,b) Conidiomata on host surface. (c–e) Section of conidiomata. (f,g) Alpha conidia attached to conidiogenous cells. (h–m) Alpha conidia. (n) 5 days old culture on PDA from above. (o) 5 days old culture on PDA from reverse. Scale bars: (c) = 100 μm, (d) = 50 μm, (e–g) = 10 μm, (h–m) = 5 μm.