Exploring the efficacy of endophytic Diaporthe caatingaensis as a biocontrol agent targeting Fusarium strains afflicting coffee plants in Saudi Arabia

Abstract

Background: The coffee plant is a strategic crop in Saudi Arabia that makes a substantial contribution to the country’s economy. Therefore, it is crucial to continuously monitor and control the fungal phytopathogens that affect coffee plants in order to minimize crop losses and ensure sustainable cultivation. This is the first surveillance report of Fusarium phytopathogens associated with coffee plants in Saudi Arabia. Moreover, the antagonistic efficiency of the endophytic fungus, Diaporthe caatingaensis, was evaluated against the isolated Fusarium phytopathogens. Methods: The isolated strains were preliminary identified using cultural and microscopic methods and the identification was confirmed using internal transcribed spacer (ITS) sequencing technique. The detached leaf assay was conducted to assess the disease severity of Fusarium phytopathogens against detached coffee leaves. Moreover, dual culture assay was utilized to assess the antagonistic activity of D. caatingaensis. Results and conclusion: Fusarium oxysporum was found to be the most frequent isolated strain followed by F. solani, F. proliferatum and F. verticillioides strains. Fusarium proliferatum strain was found to be the most severe strain whereas F. solani strain showed the lowest disease severity. On the other hand, propiconazole fungicide was tested for its efficiency against Fusarium pathogens using food poisoning technique, showing that F. oxysporum strain 1 of accession number OP955665 was the most sensitive strain. However, F. proliferatum, F. oxysporum st. 2 (OP959851) and F. solani strains showed no significant response when the propiconazole concentration increase from 150 to 200 ppm. Scanning electron microscope proved the potent antagonistic activity of D. caatingaensis against F. proliferatum and F. oxysporum OP959874 strains through mycoparasitic modes of action as coiling, appressorium formation resulting in complete lysis of fungal mycelium. Accordingly, the current investigation provides the first surveillance data about Fusarium strains associated with coffee plants and also the utilization of D. caatingaensis as a potential biocontrol agent for effective management of Fusarium phytopathogens, avoiding the incidence of fungal resistance to fungicides and the harmful effects of commercial fungicides for sustainable cultivation of coffee in Saudi Arabia.

Keywords

• Fusarium
• Phylogenetic analysis
• Diaporthe caatingaensis
• Biological control
• Mycoparasitism
• Dual culture assay