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Current status of Eastern filbert blight resistance sources and mapping

Sathuvalli, V. R., Mehlenbacher, S. A., Peterschmidt, B. C., Smith, D. C.
Acta horticulturae 2014 no.1052 pp. 27-33
Corylus avellana, alleles, blight, cultivars, disease resistance, genetic markers, greenhouses, hazelnuts, hybrids, linkage groups, loci, marker-assisted selection, microsatellite repeats, pathogens, quarantine, random amplified polymorphic DNA technique, Oregon
Eastern filbert blight (EFB), caused by the pyrenomycete Anisogramma anomala (Peck) E. Müller, is a devastating disease of European hazelnut (Corylus avellana L.) in the USA’s Pacific Northwest. Complete resistance from ‘Gasaway’, controlled by a dominant allele at a single locus, has been extensively used in the hazelnut breeding program at Oregon State University (OSU) since its discovery in 1975. Most advanced selections and the cultivars ‘Santiam’, ‘Yamhill’ and ‘Jefferson’ carry resistance from ‘Gasaway’. Concern over the breakdown of a single resistance gene prompted a continuing search for new sources of resistance. Greenhouse inoculation studies identified several sources of qualitative resistance, including accessions of C. avellana, other Corylus species and interspecific hybrids. The challenges of breeding for resistance to a pathogen absent in Corvallis, state quarantine regulations to slow its spread, its two-year life cycle, and difficulties in determining disease response stimulated a search for molecular markers linked to resistance. We have used the robust RAPD markers 152-800 and 268-580 in marker-assisted selection for ‘Gasaway’ resistance for more than a decade. Molecular markers have also been identified linked to resistance from ‘Ratoli’, OSU 759.010 and OSU 408.040. Using simple sequence repeat (SSR) markers as anchor loci, we assigned resistance from ‘Gasaway’, ‘Ratoli’, OSU 759.010, OSU 408.040 and ‘Culpla’ to linkage groups 6, 7, 2, 6 and 6, respectively. In this paper, we summarize the current status of the EFB resistance sources being used in the OSU hazelnut breeding program. For resistance loci on different linkage groups, we intend to use pyramiding with an expectation that the combined resistance will be more durable. Molecular markers linked to each source of resistance will facilitate pyramiding.