Figure 10.

Proposed model for the role of tocopherols in Arabidopsis basal resistance against compatible P. syringae. Leaf inoculation with Psm triggers strong generation of γ-tocopherol in addition to the constitutively synthesized α-tocopherol homolog, resulting in high levels of both α- and γ-tocopherol in the course of infection. The pathogen-induced biosynthesis of tocopherols proceeds essentially via the biosynthetic scheme established previously for uninfected conditions (Fig. 1), is promoted by the EDS1/PAD4 signaling node, and is induced by flagellin perception and ROS generation. The elevated tocopherol levels in infected leaves (presumably together with elevated levels of their benzoquinol precursors) protect from pathogen-induced peroxidation of triunsaturated fatty acid-containing lipids, ensure effective SA biosynthesis, and contribute to basal resistance against P. syringae.