title: Rising Out of the Ashes: Additive Genetic Variation for Crown and Collar Resistance to Hymenoscyphus fraxineus in Fraxinus excelsior.
abstract: Since the early 1990s, ash dieback due to the invasive ascomycete Hymenoscyphus fraxineus is threatening Fraxinus excelsior in most of its natural range. Previous studies reported significant levels of genetic variability in susceptibility in F. excelsior either in field or inoculation experiments. The present study was based on a field experiment planted in 1995, 15 years before onset of the disease. Crown and collar status were monitored on 777 trees from 23 open-pollinated progenies originating from three French provenances. Health status was modeled using a Bayesian approach where spatiotemporal effects were explicitly taken into account. Moderate narrow-sense heritability was found for crown dieback (h2= 0.42). This study is first to show that resistance at the collar level is also heritable (h2= 0.49 for collar lesions prevalence and h2= 0.42 for their severity) and that there is significant genetic correlation (r = 0.40) between the severities of crown and collar symptoms. There was no evidence for differences between provenances. Family effects were detected, but computing individual breeding values showed that most of the genetic variation lies within families. In agreement with previous reports, early flushing correlates with healthier crown. Implications of these results in disease management and breeding are discussed.
authors.affiliation: First, third, and fourth authors: INRA, UR 0588, Unité Amélioration, Génétique et Physiologie Forestières, CS 40001 Ardon, 45075 Orléans Cedex 2, France; and second author: INRA, Nancy Université, UMR 1136 Interactions Arbres/Microorganismes, IFR 110, F-54280 Champenoux, France.
authors.forename: Facundo
authors.identifier: 0000-0002-5061-4241
authors.initials: F
authors.lastname: Muñoz
authors.affiliation: First, third, and fourth authors: INRA, UR 0588, Unité Amélioration, Génétique et Physiologie Forestières, CS 40001 Ardon, 45075 Orléans Cedex 2, France; and second author: INRA, Nancy Université, UMR 1136 Interactions Arbres/Microorganismes, IFR 110, F-54280 Champenoux, France.
authors.forename: Benoît
authors.initials: B
authors.lastname: Marçais
authors.affiliation: First, third, and fourth authors: INRA, UR 0588, Unité Amélioration, Génétique et Physiologie Forestières, CS 40001 Ardon, 45075 Orléans Cedex 2, France; and second author: INRA, Nancy Université, UMR 1136 Interactions Arbres/Microorganismes, IFR 110, F-54280 Champenoux, France.
authors.forename: Jean
authors.initials: J
authors.lastname: Dufour
authors.affiliation: First, third, and fourth authors: INRA, UR 0588, Unité Amélioration, Génétique et Physiologie Forestières, CS 40001 Ardon, 45075 Orléans Cedex 2, France; and second author: INRA, Nancy Université, UMR 1136 Interactions Arbres/Microorganismes, IFR 110, F-54280 Champenoux, France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Dowkiw
mesh_terms: D001203:Ascomycota / Q000502:physiology*; D001499:Bayes Theorem; D031661:Fraxinus / Q000235:genetics* / Q000276:immunology / Q000382:microbiology; D014644:Genetic Variation; D015233:Models, Statistical; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology