Data from: Combining chloroplast and nuclear microsatellites to investigate origin and dispersal of New World sweet potato landraces

We analyzed a representative collection of New World sweet potato landraces (329 accessions from Mexico to Peru) with both chloroplast and nuclear microsatellite markers. Both kinds of markers supported the existence of two geographically restricted genepools, corresponding to accessions from the north-western part of South America and accessions from the Caribbean and Central America super-region. Our conservative cpSSRs markers revealed that the divergence between the two haplotype groups is associated with numerous mutation events concerning various markers, supporting the idea that this divergence may be ancient, predating domestication. For both kind of markers, we found no significant difference in diversity between the two genepools and detected region-specific alleles in both groups. Previous studies have favoured the hypothesis of a single domestication of this crop. Our analysis suggests at least two independent domestications, in Meso-America and in the north-western part of South America. Sweet potato was then dispersed from these centres throughout tropical America. Comparison of nuclear and chloroplast data suggests that exchanges of clones and sexual reproduction were both important processes in landrace diversification in this clonally propagated crop. Our analysis provides useful tools for rationalizing the conservation and use of germplasm collections.

本研究针对涵盖自墨西哥至秘鲁的新世界甘薯地方品种集合（共329份种质（accession）），采用叶绿体微卫星标记（chloroplast microsatellite markers）与核微卫星标记（nuclear microsatellite markers）进行分析。两类标记均支持存在两个地理受限基因池（genepool），分别对应南美洲西北部的种质，以及加勒比海与中美洲超区域的种质。本研究采用的保守型cpSSRs标记显示，两个单倍型类群间的分化与涉及多个标记的大量突变事件相关，这支持该分化事件发生久远、早于作物驯化的假说。针对两类标记，本研究均未发现两个基因池间的遗传多样性存在显著差异，且在两个类群中均检测到区域特异性等位基因（allele）。既往研究多支持该作物单次驯化的假说，而本研究的分析结果则表明，该作物至少存在两次独立驯化事件，分别发生在中美洲与南美洲西北部。随后甘薯从这两个驯化中心扩散至整个美洲热带区域。对核基因组与叶绿体基因组数据的比较分析显示，无性系（clone）交换与有性生殖均是该无性繁殖作物地方品种多样性形成的重要过程。本研究的分析结果可为种质资源（germplasm）收集品的合理保护与利用提供有效工具。