Analysis of the molecular dialogue between gray mold (Botrytis cinerea) and grapevine (Vitis vinifera) reveals a clear shift in defense mechanisms during berry ripening
Résumé
Mature grapevine berries at the harvesting stage (MB) are very susceptible to the gray mold fungus Botrytis cinerea while veraison berries (VB) are not. We conducted simultaneous microscopic and transcriptomic analyses of the pathogen and the host to investigate the infection process developed by B. cinerea on MB versus VB, and the plant defense mechanisms deployed to stop the fungus development. On the pathogen side, our genome-wide transcriptomic data revealed that B. cinerea genes up-regulated during infection of MB are enriched in functional categories related to necrotrophy such as degradation of plant cell wall, proteolysis, membrane transport, reactive oxygen species (ROS) generation and detoxification. Quantitative-PCR on a set of representative genes related to virulence and microscopic observations further demonstrated that the infection is also initiated on VB but stops at the penetration stage. On the plant side, genome-wide transcriptomic analysis and metabolic data revealed a defense pathways switch during berry ripening. In response to B. cinerea inoculation, VB activated a burst of ROS, the salicylate-dependent defense pathway, the synthesis of the resveratrol phytoalexin and cell-wall strengthening. On the contrary, in infected MB the jasmonate-dependent pathway was activated which did not stop the fungal necrotrophic process.