Genome Sequencing and Resource Development for European Hazelnut Cultivars

European Hazelnut (Corylus avellana) was introduced to the Pacific Northwest by early French settlers, with the moderate climate of coastal valleys being well-suited to hazelnut production. Growers in the Willamette Valley of Oregon (USA) provide nearly 99% of the hazelnuts grown in the United States, representing ~3–5% of global hazelnut production. The most common approach used in breeding hazelnuts is referred to as complementary hybridization, where the weaknesses of one parent are complemented by the strengths of the other. It is therefore of great benefit to hazelnut breeders to have genetic resources in place to take advantage of the wealth of genetic diversity while choosing parents, comprising over 700 accessions. Factors of importance when implementing a breeding strategy include resistance to disease and pathogen susceptibility. Of major concern for European hazelnut grown in the United States is the disease Eastern Filbert Blight (EFB). This disease is caused by the fungus Anisogramma anomola, which manifests itself via canker growth, ultimately leading to tree death. There are many selective breeding efforts underway in North America to identify resistant cultivars, including extensive efforts at Oregon State University. The Mehlenbacher lab at OSU is pursuing map-based cloning of the EFB resistance and pollen-stigma incompatibility loci, and recently released a resistant cultivar. This accession, “Jefferson” contains the “Gasaway” resistance gene, and was selected for Illumina next generation sequencing, assembly, and annotation to generate a reference genome for gene discovery and functional studies, as well as for developing genomic tools for breeders such a foundation for future genetic and physical maps and DNA markers to be deployed in breeding efforts. ‘Jefferson’ is currently represented by a transcriptome assembly of 28,317 transcript contigs which display high homology to available sequenced plant transcripts and have been functionally annotated with gene ontology (GO) terms. These putative gene models are currently available as a tool for homology searches and BLAST queries, with a manuscript being prepared for publication. A searchable draft genome assembly also exists, with new sequencing technology allowing for improved assemblies. Also underway is the re-sequencing of 7 additional hazelnut accessions from around the world to investigate genetic diversity and for establishment of DNA markers for agronomic traits of interest. This re-sequencing has discovered millions of SNPs between the accessions and the ‘Jefferson’ reference genome. Data will be presented on these accessions, along with the insights gained and real world applications for these new genetic resources for European hazelnut.