Differential activation of defense-related genes in susceptible and resistant pepper cultivars infected with Phytophthora capsici

• DOI: 10.1016/j.jplph.2007.11.008
• Publication Date: 2008-02-20T11:32:16Z
• Authors: Cristina Silvar; Fuencisla Merino; José Díaz
• Keywords: Phytophthora capsici; Oomycete; Pathogenesis-related protein

This study investigated the expression pattern of genes encoding for a basic PR-1 protein, a basic beta-1,3-glucanase, a peroxidase, and a sesquiterpene cyclase involved in defense responses in three pepper cultivars with different levels of resistance to Phytophthora capsici. All genes were up-regulated in infected stems of the pepper cultivars, with expression being detected 8h post-inoculation. mRNA levels of these genes increased markedly by 24h post-inoculation, and maximal induction levels were observed for the PR-1 and sesquiterpene cyclase genes. PR-1, peroxidase, and sesquiterpene genes were always expressed at higher levels in resistant cultivars than in the susceptible cultivar, although up-regulation was observed in both, suggesting that the differences between these pepper genotypes in susceptibility and resistance are a matter of the timing and magnitude of the defense response.