Biocontrol of Diseases Caused by Phytophthora capsici and P. parasitica in Pepper Plants

Abstract

The main objective of this study was to evaluate the ability of Trichoderma aggressivum f. europaeum, T. longibrachiatum, Paecilomyces variotii, and T. saturnisporum as biological control agents (BCAs) against diseases caused by P. capsici and P. parasitica in pepper. For this purpose, their antagonistic activities were evaluated both in vitro and in vivo. We analysed the expression patterns of five defence related genes, CaBGLU, CaRGA1, CaBPR1, CaPTI1, and CaSAR8.2, in leaves. All BCAs showed a high in vitro antagonistic activity, significantly reducing the mycelial growth of P. capsici and P. parasitica. The treatments with T. aggressivum f. europaeum, T. longibrachiatum, and P. variotii substantially reduced the severity of the disease caused by P. capsici by 54, 76, and 70%, respectively, and of the disease caused by P. parasitica by 66, 55, and 64%, respectively. T. saturnisporum had the lowest values of disease reduction. Reinoculation with the four BCAs increased the control of both plant pathogens. Markedly different expression patterns were observed in the genes CaBGLU, CaRGA1, and CaSAR8.2. Based on the results, all four BCAs under study could be used as a biological alternative to chemicals for the control of P. capsici and P. parasitica in pepper with a high success rate.

Phytophthora capsici the Causal Agent of Phytophthora Blight of Capsicum spp.: From Its Taxonomy to Disease Management

“…In adult plants, P. capsici infection triggers sudden leaf yellowing and wilting, resulting from the collapse of waterconducting tissues in roots and stems. This disruption of water transport marks the final disease stages, leading to plant death (Lamour et al, 2011;Barchenger et al, 2018 andSantos et al, 2023).…”

“…Managing diseases caused by P. capsici can be challenging and costly, primarily due to the overuse of Oomyceticides (previously known as fungicides). However, integrating various alternative strategies during pre-sowing, production, and post-harvest stages can significantly reduce damage and losses in Capsicum crops (Santos et al, 2023). These alternatives include: utilizing resistant ___________________________________________________________________________________________ cultivars, ensuring well-drained soil, implementing crop rotation, applying soil treatments, practicing appropriate tillage methods, managing irrigation effectively, improving irrigation water quality and employing plastic mulches (Hajji-Hedfi et al, 2023a;Hajji-Hedfi et al, 2023b;Hajji-Hedfi et al, 2023c;Rhouma et al, 2023a andRhouma et al, 2023b).…”

“…These alternatives include: utilizing resistant ___________________________________________________________________________________________ cultivars, ensuring well-drained soil, implementing crop rotation, applying soil treatments, practicing appropriate tillage methods, managing irrigation effectively, improving irrigation water quality and employing plastic mulches (Hajji-Hedfi et al, 2023a;Hajji-Hedfi et al, 2023b;Hajji-Hedfi et al, 2023c;Rhouma et al, 2023a andRhouma et al, 2023b). While, the infection of diverse Capsicum organs by P. capsici necessitates complex integrated management, the potential benefits for farmers make the effort worthwhile (Santos et al, 2023).…”

“…The staggering $100 million in annual losses attributed to P. capsici makes it the world's fifth most destructive Oomycete (Kamoun et al, 2015). Its ability to reach aerial plant tissues and 2 ___________________________________________________________________________________________ its polycyclic nature further complicate management strategies, solidifying its reputation as one of the most challenging plant pathogens to control (Santos et al, 2023 andSharma et al, 2023).…”

Application of Rhizobacteria to Control Phytophthora capsici Disease Causes Stem Base Rot and Increase Growth of Pepper Seedlings In-Vivo

“…Microbes can suppress the growth of P. capsici [7]. It was further reported that the use of biological agents could reduce the incidence of disease by up to 54-76% [8]. Furthermore, the use of microbes can also act as a bioprotectant to control P. capsici, P. infestans, and P. nicotianae diseases [9].…”