An Assay to Study Botrytis cinerea-infected Grapevine Leaves Primed with Pseudomonas fluorescens

Grapevine (Vitis vinifera L.) is susceptible to an array of diseases among them the grey mold caused by the necrotrophic fungus Botrytis cinerea that decreases grape productivity and quality. To ensure a satisfactory yield and harvest quality numerous chemical fungicides are required, but they have serious drawbacks. One alternative is the use of beneficial bacteria to improve plant health. Pseudomonas fluorescens has been shown to trigger a plant-mediated resistance response in aboveground plant tissues against fungal, oomycete, bacterial, and viral pathogens. Triggered plant resistance exploits mechanisms of the plant immune system through a priming state that provides plants with enhanced capacity for rapid and strong activation of defense responses after pathogen infection, resulting in a lower fitness-cost. The primed responses by beneficial bacteria include induced expression of defense-related genes, cell wall reinforcement, and the production of secondary metabolites after pathogen infection. In this protocol, we describe the experimental design to evaluate the priming state of grapevine plants by the beneficial bacterium Pseudomonas fluorescens PTA-CT2 and their resistance level to Botrytis cinerea according to Verhagen et al. (2011) and Gruau et al. (2015).