Newly Isolated Trichoderma spp. Show Multifaceted Biocontrol Strategies to Inhibit Potato Late Blight Causal Agent Phytophthora infestans both In Vitro and In Planta

Abstract

Potato growers worldwide have been at war for more than 150 years with an enemy whose lifecycle, genome size and architecture, infection rate, and economic impacts are the epitome of a plant pathogen. Phytophthora infestans is an oomycete that causes the notorious late blight infection in potato and tomato fields. This study explored the benefits of the multitalented plant symbiotic fungi Trichoderma spp. and their metabolites as potential biopesticides against P. infestans. Eleven strains of Trichoderma spp. were obtained from soil and tree barks and were identified using DNA sequence analysis of three molecular markers. The antagonistic potential of the strains against P. infestans was first evaluated in vitro. In dual-culture assays, P. infestans growth was significantly inhibited (53 to 95%) by different Trichoderma spp. through direct mycoparasitism, competition for space and nutrients, or antibiosis. The cell-free filtrates (CFFs) of different Trichoderma strains were obtained and characterized for anti-Phytophthora activities as well as biochemical stability. The obtained results indicated that Trichoderma CFFs were chemically stable and strongly decreased P. infestans’ mycelial growth and zoospore motility and viability. Similarly, in leaf-disk assays, Trichoderma CFFs showed significant protection against P. infestans infection. Ultraperformance liquid chromatography analysis revealed the presence of harzianic acid, iso-harzianic acid, and 6-pentyl-2H-pyran-2-one as major compounds in different Trichoderma CFFs. Furthermore, selected Trichoderma strains significantly protected potato plants against soil-mediated late blight infection. Finally, Trichoderma spp. showed high compatibility with a copper-based fungicide, especially at lower concentrations, suggesting that both protective agents could be combined in integrated pest management programs. [Graphic: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Keywords

• 6PP
• biofungicide
• biological control
• copper tolerance
• disease
• harzianic acid