The CBEL elicitor of Phytophthora parasitica var. nicotianae activates defence in Arabidopsis thaliana via three different signalling pathways

Summary •  Phytophthora parasitica var. nicotianae, an oomycete pathogen of tobacco, produces a cell wall glycoprotein named CBEL, which induces necrosis and defence responses in the host plant. Here, we investigated the elicitor activity of CBEL in Arabidopsis thaliana. •  CBEL was infiltrated into leaves of Colombia-0, and its effect on defence responses was assessed. Involvement of the signalling pathways mediated by salicylic acid (SA), jasmonic acid (JA) and ethylene (ET) was estimated by using SA-deficient transgenic plants (NahG) and two mutants affected in the perception of JA (coi1) and ET (ein2). •  We found that CBEL induced necrosis, ethylene biosynthesis, HRGP accumulation, peroxidase activity and expression of the defence-related genes ACO1, ASA1, Wak1 and PR-1 in Col-0. Necrosis induction was abolished in coi1 and ein2, whereas induction of PR-1 and Wak1 expression, HRGP accumulation and peroxidase activity was affected in NahG plants. •  Our results suggest that the three signalling pathways SA, JA and ET are involved differentially in the induction of necrosis and defence by CBEL in A. thaliana.