New Species, New Record, and Antagonistic Potential of Torula (Torulaceae, Pleosporales) from Jilin Province, China

Abstract

During a survey of ascomycetous fungi associated with plant litter and submerged wood in Jilin Province, China, two hyphomycetous fungi were discovered. Morphological examination and molecular phylogenetic analyses revealed that these isolates represent two species within the genus Torula, which are herein described as Torula changchunensis sp. nov. and a new host record of T. mackenziei. Detailed morphological characteristics are provided, and the phylogenetic relationships of the new species are also discussed. The new species differs from T. chinensis and T. phytolaccae by having smaller conidiogenous cells, smaller conidia, and fewer septa. Preliminary assessments were conducted on T. changchunensis and T. mackenziei to evaluate their antagonistic activity against two pathogenic fungi (Cladobotryum mycophilum and Botrytis cinerea) and two pathogenic bacteria (Staphylococcus aureus and Bacillus subtilis). Torula changchunensis sp. nov. exhibited 67.18% inhibition against C. mycophilum and moderate inhibition against the pathogenic bacteria, whereas Torula mackenziei showed moderate-to-weak inhibitory activity against both pathogenic fungi and bacteria.

Keywords: antifungal activity; hyphomycetous fungi; northeastern China; phylogeny; taxonomy.

Figure 1

Phylogenetic tree of Torula generated from Bayesian inference analysis based on combined ITS, LSU, SSU, tef1-α, and rpb2 sequence data. Maximum likelihood bootstrap support values ≥ 70% (ML) and Bayesian posterior probabilities ≥ 0.90 (BPP) are given at the nodes as ML/BPP. The tree is rooted with Roussoella hysterioides (CBS 125434, CBS 546.94). The type strains are in bold, and the new strains are in red.

Figure 2

Torula mackenziei (HMJAU 64848). (a) Colonies on host substrate. (b,c) Conidia in catenated chain. (d) Conidiophores with conidiogenous cells. (e–l) Conidia. (m) Culture characteristics on PDA. Scale bars: (a) = 100 μm; (b−e,g−h) = 20 μm; (f,i−l) = 10 μm.

Figure 3

Torula changchunensis (HMJAU 64900, holotype). (a–c) Colonies on host substrate. (d–g) Conidiophores with conidiogenous cells. (h–m) Conidia. (n–p) Conidia in catenated chain. (q) Culture characteristics on PDA. Scale bars: (a−c) = 500 μm; (d−g) = 5 μm; (h−p) = 10 μm.

Figure 4

In vitro growth inhibition of Torula species (left colonies) against fungal pathogens (right colonies) 7 days after the start of the confrontation. (A) CK: Botrytis cinerea vs. Bo. cinerea. (B) T. changchunensis (EMFCC 0042) vs. Bo. cinerea. (C) T. mackenziei (CCMJ 13080) vs. Bo. cinerea. (D) Control Check (CK): Cladobotryum mycophilum vs. C. mycophilum. (E) T. changchunensis (EMFCC 0042) vs. C. mycophilum. (F) T. mackenziei (CCMJ 13080) vs. C. mycophilum.

Figure 5

The antagonistic activity of Torula species against pathogenic bacteria 24 h after the start of the confrontation. (A) T. mackenziei (CCMJ 13080) vs. S. aureus. (B) T. mackenziei (CCMJ 13080) vs. B. subtilis. (C) T. changchunensis (EMFCC 0042) vs. S. aureus. (D) T. changchunensis (EMFCC 0042) vs. B. subtilis.