title: Friend or foe? Biological and ecological traits of the European ash dieback pathogen Hymenoscyphus fraxineus in its native environment.
abstract: Hymenoscyphus fraxineus, an introduced ascomycete fungus and primary causal agent of European ash dieback, was investigated on Fraxinus mandshurica trees in its native range in Primorye region of Far East Russia. This evidence is the first report of H. fraxineus on healthy, asymptomatic F. mandshurica trees. High-throughput sequencing revealed 49 distinct fungal taxa associated with leaves of F. mandshurica, 12 of which were identified to species level. Phyllosphere fungal assemblages were similar among sites despite being largely geographically distant. Many organisms comprising the foliar fungal community on F. mandshurica in Far East Russia have similarity to those reported inhabiting F. excelsior in Europe based on previous studies. However, Mycosphaerella sp., the most dominant species in this study and detected in nearly all samples, was associated only with F. mandshurica. Genetic diversity of H. fraxineus was significantly higher in the Far East Russian population than in Europe. In contrast to its aggressive behaviour on Fraxinus excelsior in Europe, H. fraxineus appears to be a benign associate of indigenous F. mandshurica that initially induces quiescent and asymptomatic infections in healthy trees prior to active host colonization normally associated with modification of host tissue during senescence.
authors.affiliation: Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, Alnarp, Sweden, Box 49, Sundsvägen 3, SE-23053 Alnarp, Sweden.
authors.forename: Michelle
authors.initials: M
authors.lastname: Cleary
authors.affiliation: Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Box 7026, Almas allé 5, SE-75007 Uppsala, Sweden.
authors.forename: Diem
authors.initials: D
authors.lastname: Nguyen
authors.affiliation: Institute of Forestry, Lithuanian Research Centre for Agriculture and Forestry, Liepų str. 1, LT-53101 Girionys, Kaunas distr., Lithuania.
authors.forename: Diana
authors.initials: D
authors.lastname: Marčiulynienė
authors.affiliation: Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Box 7026, Almas allé 5, SE-75007 Uppsala, Sweden.
authors.forename: Anna
authors.initials: A
authors.lastname: Berlin
authors.affiliation: Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Box 7026, Almas allé 5, SE-75007 Uppsala, Sweden.
authors.forename: Rimvys
authors.initials: R
authors.lastname: Vasaitis
authors.affiliation: Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Box 7026, Almas allé 5, SE-75007 Uppsala, Sweden.
authors.forename: Jan
authors.initials: J
authors.lastname: Stenlid
mesh_terms: D001203:Ascomycota / Q000235:genetics*; D060467:Disease Resistance; D005060:Europe; D031661:Fraxinus / Q000235:genetics / Q000382:microbiology*; D005800:Genes, Fungal; D017343:Genes, Plant; D020022:Genetic Predisposition to Disease; D014644:Genetic Variation; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000382:microbiology; D012426:Russia