MS1 is aimed at improving the knowledge on F. excelsior population structure and diversity along the Apennines, which are considered a putative glacial refuge. The current distribution of common ash populations in the Italian Peninsula may reflect the effect of last glaciation, and these relict populations might be characterized by a high genetic richness which is however still unexplored. As regards F. excelsior, a highly fragmented geographic distribution at the southern distribution edge, coupled with the threat due to the non-native fungus Hymenoscyphus fraxineus, poses serious challenges for natural migration of common ash to keep pace with global warming. These populations are at risk of decline, including severe genetic losses, up to extinction. The standing genetic diversity of common ash along the Italian Peninsula will be estimated through genomic data. Plant material will be sampled for clonal propagation of common ash genotypes from these populations for downstream applications.

H. fraxineus is a lethal pathogen eroding F. excelsior biodiversity in the whole Europe. Differently from what was foreseen by models the pathogen is expanding southward and reaching Mediterranean Europe. MS2 is aimed at answering the following scientific questions that are relevant for assessing the adaptation potential and invasion risk, and for optimizing the strategies for disease prevention and management: 1) Is H. fraxineus adapted to warmer Mediterranean climates?; 2) How variable are fungal populations at the epidemic front?; 3) What is the main pathway the fungus is exploiting to move southward: is it a natural range expansion by means of airborne spores or is it the consequence of human aided undeliberate introductions?