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  • Author or Editor: Vidyasagar R. Sathuvalli x
  • Journal of the American Society for Horticultural Science x
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The hundred-year history of the european hazelnut (Corylus avellana L.) industry in the Pacific northwestern United States is threatened by eastern filbert blight (EFB) caused by the fungus Anisogramma anomala (Peck) E. Müller. Marker-assisted selection has been extensively used for ‘Gasaway’ resistance in the hazelnut breeding program at Oregon State University. Concern over possible breakdown of this single resistance gene provides an incentive to look for new sources of resistance. OSU 759.010, a selection from the Republic of Georgia, has remained free of EFB after inoculations over several years. Random amplified polymorphic DNA (RAPD) markers linked to resistance were identified by screening primers against three resistant seedlings, three susceptible seedlings, and the parents of a segregating seedling population. For the progeny OSU 759.010 × OSU 653.068, 13 linked markers were identified. The markers most closely linked to resistance were 695-1800 on the proximal side and H12-640, 373-700, 349-450, and F08-700 on the distal side. Four of the five markers also segregated in the progeny OSU 759.010 × OSU 665.076, whereas H12-640 was monomorphic. Segregation for disease response in the first population showed a surplus of resistant seedlings, approaching a 3:1 ratio, with closely linked RAPD markers showing similar ratios. In the second population, the observed segregation for disease response and associated markers did not deviate from the expected 1:1 ratio. Based on cosegregation with simple sequence repeat (SSR) markers, resistance from OSU 759.010 was assigned to linkage group 2. Resistance to EFB from ‘Gasaway’ and ‘Ratoli’ was previously mapped to linkage groups 6 and 7, respectively. Therefore, OSU 759.010 provides a novel source of EFB resistance and markers 695-1800, 373-700, 349-450, and F08-700 have potential for use in marker-assisted selection to pyramid EFB resistance alleles.

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European hazelnut (Corylus avellana L.) is a significant crop in Oregon, where 99% of United States hazelnuts are produced. Eastern filbert blight (EFB) caused by Anisogramma anomala (Peck) E. Müller is an important disease that infects the trees, reduces yield, and causes premature death. Managing the disease through cultural methods and fungicide applications is laborious and expensive, and genetic host resistance is considered the most viable option for control. Genetic resistance from ‘Gasaway’ has been used to develop resistant cultivars including Yamhill and Jefferson, but concern about the durability of this single resistance gene stimulated a search for additional sources of resistance. This study used three recently identified sources of EFB resistance: ‘Culplà’ from Spain, ‘Crvenje’ from Serbia, and OSU 495.072 from southern Russia. RAPD markers linked to resistance from ‘Gasaway’ were absent in all three accessions. Disease response was noted in segregating progenies following greenhouse or structure inoculation, and the resistance loci were mapped using microsatellite markers. In only four of the nine progenies did segregation for disease response fit the ratio of 1 resistant:1 susceptible expected for a single locus, a heterozygous resistant parent, and a dominant allele for resistance. Three progenies showed an excess of resistant seedlings while two showed a deficiency of resistant seedlings. The reciprocal translocations reported in several leading hazelnut cultivars may be present in the parents of the studied progenies, and affecting the segregation ratios. Microsatellite marker A614, previously mapped to linkage group (LG) 6, was closely linked to resistance from all three sources. Maps were constructed for LG6 for each resistant parent using microsatellite markers. The three resistance loci mapped to the same region on LG6 where resistance from ‘Gasaway’ and OSU 408.040 are located. The resistance alleles in all five accessions may be the same, or more likely are a cluster of different resistance genes in the same region. Markers LG628, LG610, and LG696 will be useful to breed new hazelnut cultivars with resistance from Culplà, Crvenje, and OSU 495.072.

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