Genetic diversity and domestication of hazelnut (Corylus avellana L.) in Turkey

Abstract

Hazelnut is consumed worldwide and is of critical economic importance to the rural communities of Turkey's northern coast. A new disease outbreak has drastically decreased yields across Turkey and climate change is emerging as a new threat to cultivation. Our study is the first to provide a genomic perspective on diversity in this vulnerable crop, which will prove valuable for future breeding efforts. Such research into perennial crops like hazelnut can help to improve farmer livelihoods and ensure the sustainability of crop production in a changing world. Summary• Assessing and describing genetic diversity in crop plants is a crucial first step toward their improvement. The European hazelnut, Corylus avellana L., is one of the most economically important tree nut crops worldwide. It is primarily produced in Turkey where rural communities depend on it for their livelihoods. Despite this, we know little about its domestication history and the genetic diversity it holds.• We use double digest restriction-site associated DNA (ddRAD) sequencing to produce a genome-wide dataset containing wild and domesticated hazelnut. We uncover patterns of population structure and diversity, determine levels of crop-wild gene flow, and estimate the relationships among different genetic clusters.• We use a dataset of over 60k single nucleotide polymorphisms to find that genetic clusters of cultivars do not reflect their given names and that there is limited evidence for a reduction in genetic diversity in domesticated individuals. We find evidence that hazelnut may have been domesticated more than once and that admixture has likely occurred multiple times between wild and domesticated hazelnut.• We provide the first genomic assessment of Turkish hazelnut diversity and suggest that there has not been an extreme bottleneck during the domestication of this crop, leading to cultivars at different stages of domestication. Our study provides a platform for further research that will protect hazelnut from the threats of climate change and an emerging fungal disease. | 327 HELMSTETTER ET aL.

Unraveling Genetic Diversity Amongst European Hazelnut (Corylus avellana L.) Varieties in Turkey

“…Unlike the cultivated sub-populations, the resistant and susceptible groups had lower observed heterozygosity than expected heterozygosity, and correspondingly higher F IS . This is consistent with this group comprising largely wild accessions, that are generally more inbred than cultivated varieties (Helmstetter et al, 2020).…”

“…The nucleotide diversity (π) in most of the cultivated varieties was similar to the wild accessions (Table 2), suggesting that hazelnut has avoided the domestication bottleneck observed in many annual species (Cornille et al, 2012;Helmstetter et al, 2020). Consequently, these varieties may have preserved enough genetic diversity within the variety to adapt to changing environmental stress conditions.…”

Back to the Origins: Background and Perspectives of Grapevine Domestication

“…For example, different approaches that integrate population genomics and phylogenetic methods could be used to co-estimate both splits between subspecies and migration events. The TreeMix model [ 117 ], developed to address historical relationships, showed a good efficiency when employed to resolve the evolution of crops and their wild relatives [ 118 , 119 ], but also unravelled the intricate relationship between grape hybrids [ 81 ]. Furthermore, the D-statistics analysis (ABBA-BABA tests) have already been applied to detect introgression among sympatric populations of Asian grapes providing interesting findings [ 120 ] while inferential tools for historical demography such as Approximate Bayesian Computation (ABC) methods could be used to estimate different demographic parameters such as divergence times and migration rates.…”

A High-Density SNP Genetic Map Construction Using ddRAD-Seq and Mapping of Capsule Shattering Trait in Sesame

“…It also eliminated random shearing in the library preparation step, leading to high percentages of missing data, which is one of the major shortcomings of the genotyping-by-sequencing (GBS) method (Elshire et al, 2011). Recently, the ddRAD-Seq approach has been used successfully in different plants such as rapeseed (Chen et al, 2017), peanut (Liang et al, 2021), hazelnut (Helmstetter et al, 2020), and lettuce (Seki et al, 2020). However, to our knowledge, this study is the first time that it has been applied in sesame to construct a genetic map.…”