Hazelnut SSR database: genetic profiles of the accessions, list of synonyms, and true-to-type genotypes

Hazelnut (Corylus avellana L.) is one of the most important tree nut crops
in Europe. Germplasm accessions are conserved in ex situ repositories,
located in countries where hazelnut production occurs. In this work, we
used ten simple sequence repeat (SSR) markers as the basis to establish a
core collection representative of the hazelnut genetic diversity conserved
in different European collections. A total of 480 accessions were used:
430 from ex situ collections and 50 landraces maintained on-farm. SSR
analysis identified 181 genotypes, that represented our whole hazelnut
germplasm collection (WHGC). Four approaches (utilizing MSTRAT, Power
Core, and Core Hunter’s single- and multi-strategy) based on the
maximization (M) strategy were used to determine the best sampling method.
Core Hunter’s multi-strategy, optimizing both allele coverage (Cv) and
Cavalli-Sforza and Edwards (Dce) distance with equal weight, outperformed
the others and was selected as the best approach. The final core
collection (Cv-Dce30) comprised 30 entries (16.6% of genotypes). It
recovered all SSR alleles and preserved parameter variations when compared
to WHGC. Entries represented all six gene pools obtained from the
population structure analysis of WHGC, further confirming the
representativeness of Cv-Dce30. Our findings contribute towards improving
the conservation and management of European hazelnut genetic resources and
could be used to optimize future research by identifying a minimum number
of accessions on which to focus.

榛子（Corylus avellana L.）是欧洲最重要的坚果经济林木之一。种质资源材料保存于异位保存库中，这些保存库均设立于榛子主产国境内。
本研究以10个简单序列重复（simple sequence repeat, SSR）标记为基础，旨在构建一套能够代表欧洲不同异位保存库中保存的榛子遗传多样性的核心种质库。
本研究共使用480份材料：其中430份来自异位种质库，50份为农场保存的地方品种。通过SSR标记分析，共鉴定出181份基因型，构成了本研究的全榛子种质资源库（whole hazelnut germplasm collection, WHGC）。
研究采用四种基于最大化（maximization, M）策略的分析方法（分别依托MSTRAT、Power Core以及Core Hunter的单策略与多策略），以筛选最优采样方法。
其中，Core Hunter多策略方法在对等位基因覆盖度（allele coverage, Cv）与卡瓦利-斯福尔扎-爱德华兹距离（Cavalli-Sforza and Edwards, Dce）进行等权重优化时，表现优于其余所有方法，被选为最优方案。
最终构建的核心种质库（命名为Cv-Dce30）共包含30份材料（占总基因型数的16.6%）。与全榛子种质资源库相比，该核心库保留了全部SSR等位基因，且群体参数的变异特征得以完好保存。
该核心库覆盖了全榛子种质资源库群体结构分析所得到的全部6个基因库，进一步验证了其代表性。
本研究结果有助于优化欧洲榛子遗传资源的保存与管理工作，同时可通过明确核心研究材料的最小规模，为未来相关研究的优化提供参考。