Choquer_2021_Environ.Microbiol__

The necrotrophic plant-pathogen fungus Botrytis cinerea produces multicellular appressoria dedicated to plant penetration, named infection cushions (IC). A microarray analysis was performed to identify genes up-regulated in mature IC. The expression data were validated by RT-qPCR analysis performed in vitro and in planta, proteomic analysis of the IC secretome and biochemical assays. 1,231 up-regulated genes and 79 up-accumulated proteins were identified. The data support the secretion of effectors by IC: phytotoxins, ROS, proteases, cutinases, plant cell wall degrading enzymes and plant cell death-inducing proteins. Parallel up-regulation of sugar transport and sugar catabolism-encoding genes would indicate a role of IC in nutrition. The data also reveal a substantial remodeling of the IC cell wall and suggest a role for melanin and chitosan in IC function. Lastly, mutagenesis of two up-regulated genes in IC identified secreted fasciclin-like proteins as actors in the pathogenesis of B. cinerea. These results support the role of IC in plant penetration but also introduce other unexpected functions for this fungal organ, in colonization, necrotrophy and nutrition of the pathogen. This article is protected by copyright. All rights reserved.