CNRS-UPS-ENFA, EDB, UMR 5174, Bât. 4R1, 31062 Toulouse cedex 9, France.
Ann Bot. 2013 Nov;112(7):1293-302. doi: 10.1093/aob/mct196. Epub 2013 Sep 6.
The olive (Olea europaea subsp. europaea) was domesticated in the Mediterranean area but its wild relatives are distributed over three continents, from the Mediterranean basin to South Africa and south-western Asia. Recent studies suggested that this crop originated in the Levant while a secondary diversification occurred in most westward areas. A possible contribution of the Saharan subspecies (subsp. laperrinei) has been highlighted, but the data available were too limited to draw definite conclusions. Here, patterns of genetic differentiation in the Mediterranean and Saharan olives are analysed to test for recent admixture between these taxa.
Nuclear microsatellite and plastid DNA (ptDNA) data were compiled from previous studies and completed for a sample of 470 cultivars, 390 wild Mediterranean trees and 270 Saharan olives. A network was reconstructed for the ptDNA haplotypes, while a Bayesian clustering method was applied to identify the main gene pools in the data set and then simulate and test for early generations of admixture between Mediterranean and Saharan olives.
Four lineages of ptDNA haplotypes are recognized: three from the Mediterranean basin and one from the Sahara. Only one haplotype, primarily distributed in the Sahara, is shared between laperrinei and europaea. This haplotype is detected once in 'Dhokar', a cultivar from the Maghreb. Nuclear microsatellites show geographic patterns of genetic differentiation in the Mediterranean olive that reflect the primary origins of cultivars in the Levant, and indicate a high genetic differentiation between europaea and laperrinei. No first-generation hybrid between europaea and laperrinei is detected, but recent, reciprocal admixture between Mediterranean and Saharan subspecies is found in a few accessions, including 'Dhokar'.
This study reports for the first time admixture between Mediterranean and Saharan olives. Although its contribution remains limited, Laperrine's olive has been involved in the diversification of cultivated olives.
油橄榄（Olea europaea subsp. europaea）原产于地中海地区，但它的野生亲缘种分布在三大洲，从地中海盆地到南非和西南亚。最近的研究表明，这种作物起源于黎凡特，而在大多数向西的地区发生了二次多样化。撒哈拉亚种（subsp. laperrinei）可能有一定的贡献，但可用的数据太有限，无法得出明确的结论。在这里，分析了地中海和撒哈拉油橄榄的遗传分化模式，以检验这两个分类单元之间最近的混合情况。
从以前的研究中编译了核微卫星和质体 DNA（ptDNA）数据，并为 470 个品种、390 株野生地中海橄榄树和 270 株撒哈拉油橄榄完成了数据。为 ptDNA 单倍型重建了一个网络，同时应用贝叶斯聚类方法来识别数据集中的主要基因库，然后模拟和检验地中海和撒哈拉油橄榄之间早期的混合世代。
识别出四个 ptDNA 单倍型的谱系：三个来自地中海盆地，一个来自撒哈拉沙漠。撒哈拉和欧洲橄榄之间共享的只有一个单倍型，主要分布在撒哈拉沙漠。这个单倍型在来自马格里布的一个品种“Dhokar”中被检测到一次。核微卫星显示地中海橄榄的遗传分化具有地理模式，反映了品种在黎凡特的主要起源，并表明欧洲橄榄和撒哈拉亚种之间存在高度的遗传分化。没有检测到欧洲橄榄和撒哈拉亚种之间的第一代杂交种，但在少数几个品系中发现了地中海和撒哈拉亚种之间的近期、相互的混合，包括“Dhokar”。
本研究首次报告了地中海和撒哈拉油橄榄之间的混合。尽管其贡献仍然有限，但拉珀林的橄榄已经参与了栽培橄榄的多样化。
