Fusarium oxysporum Fo47 confers protection to pepper plants against Verticillium dahliae and Phytophthora capsici, and induces the expression of defence genes

Abstract

The application of the nonpathogenic isolate Fusarium oxysporum 47 (Fo47) reduced the symptoms of verticillium wilt, phytophthora root rot and phytophthora blight in pepper plants. Botrytis cinerea was also tested on the leaves of plants treated with Fo47, but no protection was observed. Verticillium dahliae colonies cultured in the presence of Fo47 grew slower than control cultures, but Phytophthora capsici growth was unaffected by Fo47. At least part of the protection effect observed against V. dahliae could therefore be due to antagonism or competition. In order to search for induced resistance mechanisms, three defence genes previously related to pepper resistance were monitored over time. These genes encode a basic PR-1 protein (CABPR1), a class II chitinase (CACHI2) and a sesquiterpene cyclase (CASC1) involved in the synthesis of capsidiol, a phytoalexin. These three genes were transiently up-regulated in the roots by Fo47 in the absence of inoculation with the pathogen, but in the stem only CABPR1 was up-regulated. In plants that were inoculated with V. dahliae after the Fo47 treatment, the three genes had a higher relative expression level than the control in both the roots and the stem. © 2011 The Authors. Plant Pathology © 2011 BSPP.