Deep into the apoplast: grapevine and Plasmopara viticola proteomes reveal the secret beneath host and pathogen communication at 6h after contact

Abstract

The apoplast is the first hub of plant-pathogen communication where pathogen effectors are recognized by plant defensive proteins and cell receptors, thus activating signal transduction pathways. As a result of this first contact, the host triggers a defence response that involves the modulation of extra and intracellular proteins. In grapevine-pathogen interactions, little is known about the trafficking between extra and intracellular spaces. Grapevine is an economically important crop that relies on heavy fungicide use to control several diseases, a deeper knowledge on the activation of its immune response is crucial to define new control strategies. In this study, we focused on the first 6 hours post inoculation with Plasmopara viticola to evaluate grapevine proteome modulation in the apoplast. The P. viticola proteome in planta, was also assessed enabling a deeper understanding of plant-pathogen communication. Our results showed that several plant mechanisms are triggered in the tolerant grapevine cultivar ‘Regent’ after inoculation, like oomycete recognition, plant cell wall modifications, ROS signalling and secretion of proteins to disrupt oomycete structures. On the other hand, P. viticola proteins related to development and virulence were the most predominant. This pioneer study highlights the early dynamics of cellular communication in grapevine defence that leads to the successful establishment of an incompatible interaction.