Segregation of Eastern Filbert Blight Disease Response and Single Nucleotide Polymorphism Markers in Three European–American Interspecific Hybrid Hazelnut Populations

Abstract

The perennial stem canker disease eastern filbert blight (EFB), caused by Anisogramma anomala, is devastating to most trees of European hazelnut (Corylus avellana), as genetic resistance is rare in the species. The pathogen is harbored by the wild American hazelnut (Corylus americana) found throughout much of eastern North America. Wild American hazelnut is generally resistant or tolerant to EFB, and is fully cross compatible with C. avellana, the species grown commercially for its nuts, making it a valuable resource for disease resistance breeding. The objective of this study was to identify quantitative trait loci (QTLs) associated with EFB resistance and tolerance in these two species. Three unrelated EFB-resistant C. americana selections [Oregon State University (OSU) 533.069 from Pennsylvania, OSU 403.040 from Nebraska, and OSU 557.122 from Wisconsin] were crossed with C. avellana ‘Tonda di Giffoni’ (TdG), a cultivar from Italy known to be tolerant of EFB. Their progenies, each containing 124 trees, were exposed to A. anomala through field inoculations and natural spread over 7 years, then each tree was evaluated for cumulative disease response. Results showed that disease response of all three populations exhibited a roughly normal distribution, indicating that resistance/tolerance was under multigenic control. An average of 2869 total markers were used to construct each population’s linkage map following genotyping, which included an average of 121 published simple sequence repeat markers to anchor linkage groups (LGs) to those of previous studies. Linkage maps were constructed for each parent of each population and used to map QTLs associated with EFB response. The subsequent analysis resolved five EFB-related QTLs across the three populations, highlighting three genic regions. Unexpectedly, only one QTL was identified from one of the three resistant C. americana parents, located on LG11 of the map of OSU 403.040, whereas three QTLs were found in a similar region on LG10 across the three maps of TdG, and a fifth QTL was found on LG6 of one TdG map. The lack of strong QTLs identified from the three EFB-resistant C. americana parents suggests that their resistance may be highly quantitative and not resolved within the constraints of this study. In contrast, tolerance from TdG appears to be conferred by a limited number of genes with relatively strong effects. Based on prior mapping work in European and American hazelnut where R genes have been located on LG2, LG6, and LG7, the QTLs associated with resistance/tolerance on LG10 and LG11 represent novel resistance regions. These QTLs present new targets for marker aided breeding, especially when pyramiding EFB resistance genes is a goal.

The first two chromosome‐scale genome assemblies of American hazelnut enable comparative genomic analysis of the genus Corylus

“…This gene (CamerWinkler.08G009300) is, therefore, a promising target for future functional characterization. Quantitative genetic analyses have revealed numerous loci in C. americana that are associated with EFB resistance (Komaei Koma et al ., 2021 ; Lombardoni et al ., 2022 ; Revord et al ., 2020 ), and the gene reported here could be productively included in any future studies aimed at using expression analysis or forward genetic approaches to validating their role in plant defence pathways.…”

A haplotype-resolved chromosome-level assembly and annotation of European hazelnut (C. avellanacv. Jefferson) provides insight into mechanisms of eastern filbert blight resistance

“…LG7 (Bhattarai et al, 2017;Sathuvalli et al, 2011b;Şekerli et al, 2021), LG10 and LG11 (Lombardoni et al, 2022), and more recently LG4 and LG1 (unpublished). A complete summary of resistant cultivars and their related linkage group can be found in Table 1 of Mehlenbacher et al (2023).…”

“…Recent QTL (Quantitative Trail Loci) mapping in C. americana x C. avellana mapping populations associated LG6 EFB resistance in C. avellana cv. 'Tonda di Giffoni', with SNP 93212 (Lombardoni et al, 2022). Aligning the associated paired-end sequences from SNP 93212 to 'Jefferson' V4 haplotype 1 placed the QTL peak 20 kb upstream from the markers most closely associated with EFB resistance, and within BAC contig 43F13 in the fine-mapped region defined by Sathuvalli et al (2017).…”

“…Fine mapping of the ‘Gasaway’ region using bacterial artificial chromosomes (BACs) identified a span of approximately 135 kb and five candidate EFB resistance genes (Sathuvalli et al, 2017). Other sources of EFB resistance have been identified and mapped in over 30 C. avellana cultivars and accessions, and while the majority map to LG6 (Sathuvalli et al, 2012; Colburn et al, 2015; Komaei Koma 2020), other sources of qualitative and quantitative resistance have been mapped to LG2 (Sathuvalli et al, 2011a; Şekerli et al, 2021), LG7(Bhattarai et al, 2017; Sathuvalli et al, 2011b; Şekerli et al, 2021), LG10 and LG11 (Lombardoni et al, 2022), and more recently LG4 and LG1 (unpublished). A complete summary of resistant cultivars and their related linkage group can be found in Table 1 of Mehlenbacher et al (2023).…”

Improving selection efficiency inC. americana×C. avellanainterspecific hybrids through the development of an indel-based genetic map

“…Genetic maps are an indispensable tool, in particular with regards to the former goal. While numerous genetic maps have been published using SSR (Mehlenbacher et al, 2006; Mehlenbacher and Bhattarai, 2018) and SNP markers (Rowley et al, 2018) in C. avellana backgrounds, to date, the only maps which have been generated for C. avellana × C. americana hybrid hazelnuts have utilized wild C. americana selections (Lombardoni et al, 2022). This study addresses this knowledge gap through the construction of a genetic map using an F 1 progeny family descended from a cross between Oregon and Midwestern hazelnut varieties ‘Jefferson’ and ‘Eric4-21’, respectively.…”