Quantification of Growth in .

Botrytis cinerea is one of the most devastating plant pathogens, infecting a wide array of plant species; it has also been established as a model organism to study plant-pathogen interactions. In this context, development of different assays to follow the relative success of B. cinerea infections is required. Here, we describe two methods to quantify B. cinerea development in Arabidopsis thaliana genotypes through measurements of lesion development and quantification of fungal genomic DNA in infected tissues. This provides two independent techniques that are useful in assessing the susceptibility or tolerance of different Arabidopsis genotypes to B. cinerea. Key features Protocol for the propagation of the necrotrophic plant pathogen fungus and spore production. Two methods of infection with the pathogen using droplet and spray inoculation. Two readouts, either by measuring lesion size or by the quantification of fungal DNA using quantitative PCR. The two methods are applicable across plant species susceptible the . Graphical overview A simplified overview of the droplet and spray infection methods used for the determination of growth in different genotypes.