Phytopathology (2016) 106, 1535-1543

Facundo Muñoz, Benoît Marçais, Jean Dufour and Arnaud Dowkiw (2016)
Rising out of the ashes: Additive genetic variation for crown and collar resistance to Hymenoscyphus fraxineus in Fraxinus excelsior
Phytopathology 106 (12), 1535-1543
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.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Benoit Marçais

Research topic(s) for pests/diseases/weeds:
resistance/tolerance/defence of host

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Hymenoscyphus fraxineus	Ash (Fraxinus)	France