Table_1_Genetic Identity, Diversity, and Population Structure of CIP's Sweetpotato (I. batatas) Germplasm Collection.xlsx

The in trust sweetpotato collection housed by the International Center of Potato (CIP) is one of the largest assemblages of plant material representing the genetic resources of this important staple crop. The collection currently contains almost 6,000 accessions of Ipomoea batatas (cultivated sweetpotato) and over 1,000 accessions of sweetpotato crop wild relatives (CWRs). In this study, the entire cultivated collection (5,979 accessions) was genotyped with a panel of 20 simple sequence repeat (SSR) markers to assess genetic identity, diversity, and population structure. Genotyping and phenotyping of in vitro plantlets and mother plants were conducted simultaneously on 2,711 accessions (45% of the total collection) to identify and correct possible genetic identity errors which could have occurred at any time over the thirty plus years of maintenance in the in vitro collection. Within this group, 533 accessions (19.6%) had errors in identity. Field evaluations of morphological descriptors were carried out to confirm the marker data. A phylogenetic tree was constructed to reveal the intraspecific relationships in the population which uncovered high levels of redundancy in material from Peru and Latin America. These genotypic data were supported by morphological data. Population structure analysis demonstrated support for four ancestral populations with many of the accessions having lower levels of gene flow from the other populations. This was especially true of germplasm derived from Peru, Ecuador, and Africa. The set of 20 SSR markers was subsequently utilized to examine a subset of 189 accessions from the USDA sweetpotato germplasm collection and to identify and reconcile potential errors in the identification of clones shared between these collections. Marker analysis demonstrated that the USDA subset of material had 65 unique accessions that were not found in the larger CIP collection. As far as the authors are aware, this is the first report of genotyping an entire sweetpotato germplasm collection in its entirety.

由国际马铃薯中心（International Center of Potato, CIP）受托保管的甘薯种质资源库，是当前涵盖这一重要主粮作物遗传资源的规模最大的植物材料集合之一。该种质库目前保存有近6000份栽培甘薯（Ipomoea batatas）种质，以及超过1000份甘薯作物野生近缘种（Crop Wild Relatives, CWRs）种质。本研究针对全部栽培种质资源库（共计5979份种质），采用20个简单序列重复（Simple Sequence Repeat, SSR）标记组合开展基因分型，以解析其遗传同一性、遗传多样性及群体结构。同时，研究人员对占总种质库45%的2711份种质的离体培养苗及母本植株同步开展基因分型与表型鉴定，以识别并校正该离体保存库历经三十余年管护过程中可能出现的遗传同一性错误。其中，533份种质（占该亚群的19.6%）存在同一性偏差。随后通过形态学描述符田间评价，对分子标记数据进行验证。研究构建了系统发育树以揭示该群体内的种内亲缘关系，结果发现秘鲁及拉丁美洲地区的材料存在较高水平的遗传冗余。上述基因型数据得到了表型数据的佐证。群体结构分析显示，该种质资源可划分为4个祖先类群，多数种质与其他类群间的基因流水平较低，其中源自秘鲁、厄瓜多尔及非洲的种质尤为显著。后续，研究团队利用这套20个SSR标记组合，对美国农业部（USDA）甘薯种质库中的189份亚群种质进行分析，识别并修正了两个种质库间共享克隆株系鉴定过程中存在的潜在错误。分子标记分析表明，USDA该亚群材料中存在65份未在规模更大的CIP种质库中出现的独特种质。据作者所知，本研究是首次对完整的甘薯种质资源库开展全范围基因分型的报道。