Genomic characterization of a global Corylus avellana L. collection: insights into hazelnut ancestry and genetic determinants of production traits

Abstract

Background European Hazelnut (Corylus avellana L.) is a high-value, understudied crop that exhibits a large diversity of traits. Commercial production relies on a small number of globally grown varieties. Advancing hazelnut breeding requires a comprehensive understanding of its genetic diversity and its association with valuable traits. Here, we used genotyping-by-sequencing to sequence 316 hazelnut varieties, retaining 282 samples and 44,757 single nucleotide polymorphisms (SNPs) after quality control. This collection was used to study genetic diversity, identify genomic loci under selection, and describe genome-wide association with nut traits, i.e. nut size, perimeter and caliber. Results We uncovered three genetic clusters and five ancestral populations, with Eurasian varieties (Türkiye, Azerbaijan, and Georgia) being the most distinct and European and U.S. populations showing higher admixture. We identified four loci under positive selection in Eurasian varieties, including one within Cav06g02620 (probable calcium uniporter) on chromosome 6. We also characterized the nut morphology of 151 genotyped varieties, leading to the identification of ten SNPs associated with nut traits. Conclusions While functional validation of candidate genes and the use of a larger population are important for future analysis, our findings provide a basis for exploring the genetics of quantitative traits in hazelnut, supporting breeding and conservation efforts.