Genetic variation of resistance in Scots pine as possible solution against Diplodia sapinea

With ongoing climate change, the risk caused by both native, well-known pathogens and new, invasive ones is increasing. Diplodia sapinea (Fr.) Fuckel is responsible for Diplodia tip blight, a new fungal disease in Finland, that kills the current-year shoots of Scots pine (Pinus sylvestris L.). This can lead to the death of young trees and increase the susceptibility of trees of all ages to other stressors. Since D. sapinea spreads by airborne spores, it cannot be eradicated. In this study, we present the first screening to evaluate the potential for harnessing the genetic variation of Scots pine to improve its resilience against D. sapinea. Further, we wanted to test if predisposing this warm-preferring pathogen to higher temperature will increase its virulence. On the contrary, higher temperature initially reduced the virulence of D. sapinea, but the effect diminished over time. Based on necrosis length, we observed between-family variation in seedling resistance. These findings support the need for larger future trials to explore the potential for harnessing genetic variation to enhance resistance against D. sapinea.