New Insights into the Mechanism of Trichoderma virens-Induced Developmental Effects on Agrostis stolonifera Disease Resistance against Dollar Spot Infection

Abstract

Trichoderma is internationally recognized as a biocontrol fungus for its broad-spectrum antimicrobial activity. Intriguingly, the crosstalk mechanism between the plant and Trichoderma is dynamic, depending on the Trichoderma strains and the plant species. In our previous study, the Trichoderma virens 192-45 strain showed better pathogen inhibition through the secretive non-volatile and volatile substrates. Therefore, we studied transcriptional and metabolic responses altered in creeping bentgrass (Agrostis stolonifera L.) with T. virens colonization prior to a challenge with Clarireedia homoeocarpa. This fungal pathogen causes dollar spot on various turfgrasses. When the pathogen is deficient, the importance of T. virens to the enhancement of plant growth can be seen in hormonal production and microbe signaling, such as indole-3-acrylic acid. Therefore, these substrates secreted by T. virens and induced genes related to plant growth can be the ‘pre-defense’ for ensuing pathogen attacks. During C. homoeocarpa infection, the Trichoderma–plant interaction activates defense responses through the SA- and/or JA-dependent pathway, induced by T. virens and its respective exudates, such as oleic, citric, and stearic acid. Thus, we will anticipate a combination of genetic engineering and exogenous application targeting these genes and metabolites, which could make creeping bentgrass more resistant to dollar spot and other pathogens.

Antifungal mechanism of cell-free supernatant produced by Trichoderma virens and its efficacy for the control of pear Valsa canker

“…VOCs, 2,4-di-tert-butylphenol and 4-methyl-1-pentanol, released by Aspergillus niger strain La2, are promising novel candidate biocontrol agents for the control of pear Valsa canker ( Shi et al, 2024 ). T. virens and its emitted metabolites, including linolenic acid, fumaric acid, and citric acid, were reported to possess antifungal activity and influence pathogen metabolism ( Gan et al, 2022 ). The metabolites are effective antifungal compounds that interfere with critical processes in target pathogens and enhance the competitive ability of biocontrol strains.…”

“…The antibiosis mechanism involved in the interaction between Trichoderma and pathogen is driven by a variety of primary and secondary metabolites secreted by Trichoderma . These metabolites, including fatty acids, organic acids, terpenes, amides, and others ( Zhang et al, 2018 ; Gan et al, 2022 ; Zaid et al, 2022 ), have broad-spectrum antimicrobial activity in their ecological niches, can destroy cell membrane, and inhibit mycelium growth or spore germination of the targeted pathogen. A previous study showed that fermentation of Trichoderma longibrachiatum T6 could exert antifungal effects on the pathogen V. mali of apple Valsa canker, such as inhibiting conidia germination, altering mycelial morphology, and blocking growth ( Zhu et al, 2022 ).…”

“…Research involving an assay targeting Rhizoctonia solani and nematode mortality has demonstrated that the suppression of these pathogens can be attributed to the antibiosis mechanism of Trichoderma virens metabolites ( Halifu et al, 2020 ; Moo-Koh et al, 2022 ). These metabolites functioned as inhibitors, facilitating the penetration of Trichoderma hyphae into prey fungi and hampering vital processes such as cell wall synthesis, growth, reproduction, sporulation, nutrient uptake, metabolite production in target pathogens, and induction of defense system ( Halifu et al, 2020 ; Gan et al, 2022 ; Zhu et al, 2022 ). However, the function of T. virens on antifungal activity on V. pyri remains to be explored.…”