Inheritance and Linkage Mapping of Eastern Filbert Blight Disease Resistance in ‘Uebov’ Hazelnut

Abstract

<jats:p>Eastern filbert blight (EFB) is a serious fungal disease of european hazelnut (<jats:italic>Corylus avellana</jats:italic>) in North America. The causal agent is the pyrenomycete <jats:italic>Anisogramma anomala</jats:italic>, which is native in the eastern United States where it occasionally produces small cankers on the wild american hazelnut (<jats:italic>C. americana</jats:italic>). However, most commercial cultivars of european hazelnut are susceptible. Infection leads to perennial cankers, girdling of branches, and premature tree death. Cultural practices including scouting, pruning out infected branches, and fungicide applications are recommended to slow disease spread but are expensive and not completely effective. EFB resistance from ‘Gasaway’ is conferred by a dominant allele at a single locus and has been extensively used in the Oregon State University hazelnut breeding program, but there is concern that this resistance could be overcome by isolates now present in the eastern United States or that a new race of the pathogen could arise in Oregon. Segregation for EFB resistance from ‘Uebov’, a new source from Serbia, was studied in three progenies by a combination of structure exposure and greenhouse inoculation. The frequency of resistant seedlings following structure exposure was about 20% in all three progenies. The ratios failed to fit the expected 1:1 ratio but did fit a ratio of 1 resistant:3 susceptible, which would be expected if resistance were conferred by dominant alleles at two independent loci. Seedlings from a cross of susceptible selection OSU 741.105 and ‘Uebov’ were used to study correlation of disease response and presence of alleles at microsatellite marker loci. Resistance was highly correlated with the presence of alleles at marker loci on linkage group 6 (LG6), and these markers also showed segregation distortion. We conclude that EFB resistance from ‘Uebov’ maps to a single locus on LG6 in the same region as resistance from ‘Gasaway’, although only about 20% of the seedlings are resistant because of segregation distortion. ‘Uebov’ has large, well-filled, round nuts and is suitable as a parent in breeding for the in-shell market, but its low nut yields and a high frequency of shells with split sutures are the drawbacks. Its use would expand options for breeding and ‘Uebov’ resistance could be combined with other resistance alleles with an expectation of more durable EFB resistance. Durable resistance would not only sustain the hazelnut industry in Oregon but would also allow expansion of plantings to new areas.</jats:p>

New Sources of Eastern Filbert Blight Resistance and Simple Sequence Repeat Markers on Linkage Group 6 in Hazelnut (Corylus avellana L.)

“…The one progeny segregating for resistance from 'Moscow #37' had an excess of susceptible seedlings. An excess of susceptible seedlings was reported in previous EFB resistance studies in hazelnut (Colburn et al, 2015;Bhattarai et al, 2017b). Lunde et al (2006) noted an excess of resistant seedlings in the offspring of 'Zimmerman' , and that even when SSR markers indicate that the resistance gene is present, small cankers occasionally develop.…”

“…Previously studied resistance sources include OSU 408.040 from Minnesota, ‘Culpla’ from Spain, OSU 495.072 from southern Russia, and ‘Crvenje’ and ‘Uebov’ from Serbia. Resistance from all five of these sources was placed on linkage group 6 (LG6) in the ‘Gasaway’ resistance region ( Sathuvalli et al, 2012 ; Colburn et al, 2015 ; Bhattarai et al, 2017b ). On the other hand, resistance in ‘Ratoli’ from Spain, C. americana ‘Rush’ from Pennsylvania and interspecific hybrid ‘Yoder #5’ from Ohio was assigned to a region on LG7 ( Sathuvalli et al, 2011a ; Bhattarai et al, 2017a ).…”

New Simple Sequence Repeat Markers on Linkage Groups 2 and 7, and Investigation of New Sources of Eastern Filbert Blight Resistance in Hazelnut

“…However, deviation from the expected 1:1 segregation ratio (resistance: susceptible) was seen in four progenies in this study. In several previous studies, segregation distortion for EFB response was observed for 'Culpla', 'Crvenje', Russian OSU 495.072 (Colburn et al, 2015), 'Uebov' (Bhattarai et al, 2017a), and 'Zimmerman' (Lunde et al, 2006). In some progenies, there is an excess of resistant seedlings; while in others, there is an excess of susceptible seedlings.…”

“…Additional sources of EFB resistance have been identified and assigned to LGs. Resistance in OSU 408.040 from Minnesota (Sathuvalli et al, 2012), OSU 495.072 from Russia, 'Culpla' from Spain, and 'Crvenje' and 'Uebov' from Serbia (Bhattarai et al, 2017a;Colburn et al, 2015) was assigned to LG6. Resistance in 'Ratoli' from Spain (Sathuvalli et al, 2011a), C. americana 'Rush', and interspecific hybrid 'Yoder #5' (Bhattarai et al, 2017b) was assigned to LG7.…”

Genetic Analysis of the Cultivars of Ping’ou Hybrid Hazelnut (C. heterophylla Fisch. × C. avellana L.) in China Based on SSR Markers

“…SSR markers have the distinguishing features of multi-allelic, co-dominant inheritance patterns, reproducibility, high polymorphism, locus specificity, and transferability to related species and genera [5]. At present, more than 700 SSR loci have been developed in Corylus [6][7][8][9][10][11][12][13], and have been widely used in population structure assessment [14][15][16], germplasm identification and genetic diversity analysis [17][18][19][20], linkage map construction [21][22][23][24], and molecular marker-assisted selection [25,26]. In our previous study, we identified some cultivars of Ping'ou hybrid hazelnut by using the EST-SSR markers we developed in a pistil transcriptome [27].…”