The American hazelnut (Corylus americana) is native to a broad range of the eastern United States and southern Canada. It is the endemic host of the fungus Anisogramma anomala, which causes eastern filbert blight (EFB) disease and limits European hazelnut (C. avellana) production in eastern North America. While C. americana has thick-shelled, tiny nuts not suited for commercial production, it is cold hardy, highly tolerant of EFB, and phenotypically diverse. Previous studies with simple sequence repeat markers show that it is also genetically diverse. Further, the species is cross-compatible with C. avellana and is thus a valuable donor of EFB resistance and climate adaptability traits. However, only a narrow set of C. americana parents has been used in interspecific hybridizations, and current germplasm availability likely does not fully represent the species’ genetic diversity, given its vast range. A new collection of open-pollinated C. americana seed was assembled at Rutgers University to broaden available genetic resources. Here, we study the genetic diversity and population structure of 272 of these individuals, which represent 55 seedlots from across 15 states of the species’ native range. We use multivariate analyses to examine the distribution of genetic variation within the collection and to support the identification of a core set. A genotyping-by-sequencing (GBS) approach yielded 2653 single nucleotide polymorphisms and subsequent analyses revealed a collection with high estimates of heterozygosity (H_E = 0.276, H_O = 0.280), moderate differentiation (F_ST = 0.108) and low inbreeding (F_IS = −0.136). Bayesian model-based and neighbor-joining (NJ) clustering corroborate an uppermost grouping of K = 3, with the NJ dendrogram depicting many small subgroups equally distant from common ancestry. Discriminant analysis of principal components (DAPC) reveals between-subgroup variation (K = 15) within the NJ dendrogram and allows the identification of 19 consensus subgroups. In general, our results support the assembly of a genetically diverse collection where a majority of the variation is explained at the genotype and subgroup levels, which aligns with previous studies of C. americana. Fifty-one accessions were identified that represent 95% of the observed allelic variation. These genotypes are suggested for inclusion in a core collection, which, when coupled to concurrent phenotypic evaluations, will aid in genetic resource assembly that preserves unique phenotypes and retains genetic variation.

美国榛子（Corylus americana）原产于美国东部和加拿大南部。它是真菌Anisogramma anomala的地方性宿主，它引起东部欧洲榛树病（EFB）疾病，并限制了北美东部欧洲榛子（C. avellana）的生产。尽管美洲锦鸡有不适合商业生产的厚壳小坚果，但它耐寒，对EFB的耐受性强，并且表型多样。以前使用简单的序列重复标记进行的研究表明，它在遗传上也是多样的。此外，该物种与C. avellana交叉兼容因此，它是EFB抗性和气候适应性状的宝贵捐助者。然而，在种间杂交中仅使用了少量的美洲锦鸡亲本，鉴于其广泛的种类，目前的种质利用率可能无法完全代表该物种的遗传多样性。公开授粉的美洲锦葵的新收藏种子在罗格斯大学（Rutgers University）组装，以扩大可用的遗传资源。在这里，我们研究了这些个体中272个个体的遗传多样性和种群结构，这些个体代表了该物种自然分布的15个州的55个种子场。我们使用多元分析来检查集合内遗传变异的分布并支持核心集的识别。测序基因分型（GBS）方法产生2653个单核苷酸多态性，随后的分析表明该集合具有较高的杂合性估计值（H _E  = 0.276，H _O  = 0.280），中等分化（F _ST  = 0.108）和近交低（˚F _IS = -0.136）。基于贝叶斯模型和邻居加入（NJ）的聚类证实了K  = 3的最上层分组，NJ树状图描绘了许多距离共同祖先相等距离的小子群。主成分（DAPC）的判别分析揭示 了NJ树状图内的亚组间差异（K = 15），并允许识别19个共有亚组。总的来说，我们的结果支持了遗传多样性集合的集合，其中大部分变异是在基因型和亚组水平上解释的，这与以前对美洲梭菌的研究一致。鉴定出五十一个种质，代表观察到的等位基因变异的95％。建议将这些基因型包括在核心收藏夹中，当与同时进行的表型评估结合时，将有助于遗传资源的组装，保留独特的表型并保留遗传变异。