Data from: On the origin of sweet potato (Ipomoea batatas (L.) Lam) genetic diversity in New Guinea, a secondary centre of diversity

New Guinea is considered the most important secondary centre of diversity for sweet potato (Ipomoea batatas). We analysed nuclear and chloroplast genetic diversity of 417 New Guinea sweet potato landraces, representing agro-morphological diversity collected throughout the island, and compared this diversity with that in tropical America. The molecular data reveal moderate diversity across all accessions analysed, lower than that found in tropical America. Nuclear data confirm previous results, suggesting that New Guinea landraces are principally derived from the Northern neotropical genepool (Camote and Batata lines, from the Caribbean and Central America). However, chloroplast data suggest that South American clones (early Kumara line clones or, more probably, later reintroductions) were also introduced into New Guinea and then recombined with existing genotypes. The frequency distribution of pairwise distances between New Guinea landraces suggests that sexual reproduction, rather than somaclonal variation, has played a predominant role in the diversification of sweet potato. The frequent incorporation of plants issued from true seed by farmers, and the geographical and cultural barriers constraining crop diffusion in this topographically and linguistically heterogeneous island, has led to the accumulation of an impressive number of variants. As the diversification of sweet potato in New Guinea is primarily the result of farmers’ management of the reproductive biology of their crop, we argue that on-farm conservation programmes that implement distribution of core samples (clones representing the useful diversity of the species) and promote on-farm selection of locally adapted variants may allow local communities to fashion relatively autonomous strategies for coping with ongoing global change.

新几内亚被认为是甘薯（Ipomoea batatas）最重要的次生多样性中心。本研究对覆盖全岛采集、涵盖农业形态多样性的417份新几内亚甘薯地方品种开展核基因组与叶绿体基因组遗传多样性分析，并将该多样性与热带美洲的甘薯遗传多样性进行对比。分子数据显示，所有供试种质的遗传多样性处于中等水平，且低于热带美洲的甘薯遗传多样性。核基因组数据验证了此前的研究结论，表明新几内亚甘薯地方品种主要起源于新热带北部基因库（来自加勒比海与中美洲的Camote和Batata品系）。然而，叶绿体基因组数据显示，南美克隆（早期Kumara品系克隆，或更可能为后期再次引入的材料）同样被引入新几内亚，并与当地原有基因型发生重组。新几内亚甘薯地方品种间的两两遗传距离频率分布表明，有性生殖而非体细胞无性系变异，在甘薯的多样化进程中发挥了主导作用。农民频繁利用实生种子培育的植株进行种植，加之该岛地形复杂、语言多元，存在限制作物扩散的地理与文化壁垒，共同促成了大量变异类型的积累。鉴于新几内亚甘薯的多样化进程主要源于农户对作物生殖生物学的管理，我们认为，推行核心样本（代表该物种有用遗传多样性的克隆材料）分发、并鼓励农户原位选择适应本地环境的变异类型的农田原位保护计划，可使当地社区制定相对自主的策略，以应对持续的全球变化。