Abstract：
The sweet cherry is an important fruit species that is widespread globally. In addition to the well-known traditional and modern varieties, a myriad of landraces is present in Europe, as well as in southern Italy. This study aims to evaluate the population structure, genetic relationships, and cases of duplicate samples in a collection of 143 accessions using GBS-derived SNP markers. The genetic material under investigation includes modern commercial varieties, ancient European and American varieties, landraces, and individuals retrieved from small orchards. Some of the known varieties were genetically analyzed here for the first time. In addition, several genotypes were collected from the Basilicata region (southern Italy), an area largely unexplored for sweet cherry genetic resources. The relationships among genotypes were assessed using four different methods: allele frequency and ancestry estimation, principal component analysis, Neighbor-Joining tree, and identity-by-state estimation. The analyses returned quite congruent results and highlighted the presence of four main genetic groups, namely: (i) American varieties, (ii) the \'Germersdorfer-Ferrovia\' cluster, (iii) the \'Burlat\' group, and (iv) the group of Italian landraces. The main drivers of clustering were ancestry, geographical distribution, and some important traits such as self-compatibility. The sweet cherries from Basilicata, herewith examined for the first time, were mostly distributed within the group of Italian landraces, being particularly linked to the autochthonous varieties of the Campania region. However, some genotypes were outside this group, thus suggesting the introduction of genetic material from other Italian regions or from European countries. The considerable amount of American and European modern varieties analyzed are genetically very closely related, suggesting a reduced genetic basis. In addition, we highlighted the discriminating ability of SNP markers to distinguish between an original variety and its mutant. Overall, our results may be useful in defining conservation strategies for sweet cherry germplasm and developing future breeding programs to enlarge the genetic basis of commercial varieties.
摘要：
甜樱桃是一种重要的水果品种，在全球范围内普遍存在。除了著名的传统和现代品种，欧洲有无数的地方品种，以及意大利南部。本研究旨在评估人口结构，遗传关系,以及使用GBS衍生的SNP标记在143个种质的集合中重复样本的情况。正在调查的遗传物质包括现代商业品种，古老的欧洲和美洲品种，地方品种,和从小果园中找到的个体。这里首次对一些已知品种进行了基因分析。此外,从Basilicata地区（意大利南部）收集了几种基因型，一个尚未开发甜樱桃遗传资源的地区。使用四种不同的方法评估基因型之间的关系：等位基因频率和祖先估计，主成分分析，邻居-加入树，和按状态身份估计。分析返回了相当一致的结果，并强调了四个主要遗传群体的存在，即：(I)美国品种，(ii)“Germersdorfer-Ferrovia”集群，(iii)“Burlat”组，和（iv）意大利地方种族组。聚类的主要驱动因素是祖先，地理分布,和一些重要的特征，如自我兼容性。来自Basilicata的甜樱桃，本文首次检查，主要分布在意大利本土种族中，特别与坎帕尼亚地区的本土品种有关。然而,一些基因型在这个群体之外，因此建议从其他意大利地区或欧洲国家引入遗传物质。分析的相当数量的美国和欧洲现代品种在遗传上非常密切相关，表明遗传基础减少。此外,我们强调了SNP标记区分原始品种及其突变体的辨别能力。总的来说,我们的结果可能有助于确定甜樱桃种质的保护策略，并制定未来的育种计划，以扩大商业品种的遗传基础。
