Resistance against Dickeya solani in potato with the help of a susceptibility gene

Potato (Solanum tuberosum) is a staple crop across Europe, including Sweden. Among the reasons why it is so ubiquitous is its fairly easy cultivation, good adaptability to various climates, and high nutritional value. Today’s potato production is based on disease-free seed tubers. However, this technology often proves to be insufficient. Seed tubers serve as a target for accumulation of pests and pathogens, and one such pathogen is the necrotrophic bacterium Dickeya solani, which causes blackleg and soft rot. Due to its ability to macerate plant tissue and cause severe damages in the field, it is responsible for substantial yield losses across Europe. Consequentially, D.solani is treated as a quarantine organism in some countries. More importantly for this study, its presence has been reported in Sweden. In the present study, a new approach to potentially offer a durable and broad-spectrum disease resistance towards D. solani and some other pathogens isexplored. Susceptibility genes encode products that are required for the pathogen’s survival or proliferation, thus making a plant more susceptible to disease development. By silencing the homologs of the susceptibility gene Downy Mildew Resistant 6 (DMR6) in diploid DM1-3516 R44 and tetraploid Desirée background using RNA interference, an enhanced resistance was anticipated. Pleiotropic growth effects of DMR6 silencing were investigated and greenhouse-based infection assays were carried out. Two silenced RNAi silenced Desirée lines were tested, however, only one (dmr6-6) showed promising results as it repeatedly had smaller blackleg symptoms, high constitutive PR-1 expression, and showed no developmental and growth impairments compared to the corresponding wild