Inhibition of plant pathogenic fungi by endophytic Trichoderma spp. through mycoparasitism and volatile organic compounds

Microbiol Res. 2021 Jan:242:126595. doi: 10.1016/j.micres.2020.126595. Epub 2020 Sep 17.

Abstract

Antagonism of plant pathogenic fungi by endophytic fungi is a well-known phenomenon. In plate assays, the antagonism could be due to mycoparasitism, competition for space or antibiosis, involving a chemical diffusate, or a volatile organic compound (VOC). In this study, we demonstrate that besides mycoparasitism, VOCs play a major role in antagonism of pathogenic fungi by four endophytic fungi belonging to the genus Trichoderma. Using a double-plate assay, we show that all the four endophytic Trichoderma species significantly inhibited mycelial growth of three of the four pathogens, (Sclerotinia sclerotiorum-TSS, Sclerotium rolfsii-CSR and Fusarium oxysporum-CFO), while that of Macrophomina phaseolina-CMP was not affected. GC-MS analysis of the pure cultures of one of the endophytic fungi studied, namely, Trichoderma longibrachiatum strain 2 (Acc. No. MK751758) and the pathogens, F. oxysporum-CFO and M. phaseolina-CMP revealed the presence of several VOCs including hydrocarbons, alcohols, ketones, aldehydes, esters, acids, ethers and different classes of terpenes. In mixed double plates, where the endophyte was grown along with either of the two plant pathogens, F. oxysporum-CFO or M. phaseolina-CMP, there was an induction of a number of new VOCs that were not detected in the pure cultures of either the endophyte or the pathogens. Several of these new VOCs are reported to possess antifungal and cytotoxic activity. We discuss these results and highlight the importance of such interactions in endophyte-pathogen interactions.

Keywords: Biological control; Endophytic fungi; Fungal antagonism; Soil-borne pathogenic fungi.

MeSH terms

  • Antibiosis
  • Antifungal Agents / pharmacology
  • Ascomycota
  • Biological Control Agents
  • Endophytes / drug effects
  • Fungi / drug effects*
  • Fusarium / drug effects
  • Hypocreales
  • Plant Diseases / microbiology*
  • Plants / microbiology*
  • Trichoderma / classification
  • Trichoderma / isolation & purification
  • Trichoderma / metabolism*
  • Volatile Organic Compounds / pharmacology*

Substances

  • Antifungal Agents
  • Biological Control Agents
  • Volatile Organic Compounds

Supplementary concepts

  • Fusarium oxysporum
  • Macrophomina phaseolina
  • Sclerotinia sclerotiorum
  • Trichoderma longibrachiatum