Comparative analysis of infection and defensive strategies associated with powdery mildew disease in grapevine and strawberry

Abstract

Domesticated strawberry and grape are fruits of very significant commercial and nutritional importance worldwide. However, they are, respectively, highly susceptible to infection by Podosphaera aphanis and Erysiphe necator fungi causing powdery mildew. Fungicide application has effectively controlled powdery mildew; however, fungicides cause pathogen resistance and affect environmental and human health. Additionally, loss of active ingredients associated with stricter European regulations created new challenges.

Previously, we showed that susceptible grapes activate defence responses associated with PAMP-triggered immunity and effector-triggered immunity, together with salicylic acid- and jasmonate-related pathways and the accumulation of defence-associated metabolites, although these responses were insufficient to restrict fungal progression. Some of these responses were shared with leaves, while others were organ-specific. Asimilar workflow strategy (transcriptomics coupled with metabolomics and targeted metabolic profiling) is being used with strawberry leaves and fruits to understand the basis of organ susceptibility and resistance/ tolerance across two non-climacteric fruits challenged by two different PM fungi with the same lifestyle. These data will support the selection of candidate genes for CRISPR-Cas9-based mutagenesis aiming at improving powdery mildew resilience. Optimisation of in vitro culture processes required for plantlet transformation and regeneration is under investigation. Additionally, in silico analysis of the Podosphaera aphanis and Erysiphe necator secretome, and identification of putative powdery mildew-specific core effectome assisted by RNAseq data is being carried out to decipher the mechanisms of fungal virulence under host defensive strategies.

Altogether, this data will contribute to mitigate the impact of powdery mildew in two important fruit species.