Identification of genomic regions for general and host specific virulence in the fruit canker fungus Neonectria ditissima by genome-wide association analysis
Fruit Tree Canker (FTC) caused by the fungus Neonectria ditissima is one of the most serious diseases in Swedish apple orchards and in many other European countries. Taking into account high costs for establishment of a new orchard (~400 tkr/ha), FTC threatens the apple production. N. ditissima is known to also be able to attack several forest hardwood tree species e.g. Acer, Betula, Fagus, Fraxinus, Populus, Quercus and Salix. It is spread aerially and by rain splashing and is able to infect throughout the year through already existing wounds. The outcome of this project will be an increased understanding of the N. ditissima – poplar/apple pathosystems by associating genomic regions with fungal virulence and generating a list of candidate virulence genes. We hypothesize that there has been a single introduction of the pathogen to Sweden from Europe through trade of apple material which would lead to a low genetic variability and absence of population structure in Sweden. The increased knowledge of the apple – N.ditissima – poplar pathosystems in Europe will not only strengthen basic research but will allow us to assess the inoculum pressure within and around apple orchards, help nursery managers decide on sources of plant material and enable us to screen orchards for highly and less virulent isolates respectively.