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

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.

Automated summary

The aim of this study was to evaluate the effectiveness of Trichoderma aggressivum f. europaeum, T. longibrachiatum, Paecilomyces variotii, and T. saturnisporum as biological control agents against diseases caused by P. capsici and P. parasitica in pepper. In vitro and in vivo experiments were conducted to assess their antagonistic activities, and the expression patterns of five defense-related genes were analyzed in leaves. All four BCAs showed significant in vitro antagonistic activity against P. capsici and P. parasitica. Treatment with T. aggressivum f. europaeum, T. longibrachiatum, and P. variotii effectively reduced disease severity caused by both pathogens, while T. saturnisporum had the lowest effectiveness. Reinoculation with the BCAs improved disease control. The study suggests that these BCAs can be used as an alternative to chemicals to control pepper diseases with high success rates.