G. Besnard1,2⇓, B. Khadari3, M. Navascués4, M.
Fernández-Mazuecos5, A. El Bakkali3, N. Arrigo6, D. Baali-Cherif7, V. Brunini-Bronzini
de Caraffa8, S. Santoni3, P. Vargas5 and V. Savolainen2,9
Author Affiliations
1CNRS-UPS-ENFA, EDB, UMR 5174, Bât. 4R1, 31062 Toulouse
Cedex 9, France
2Imperial College London, Silwood Park Campus, Ascot SL5
7PY, UK
3INRA/CBNMED, UMR 1334, AGAP, 34060 Montpellier, France
4INRA, UMR1062 CBGP, 34988 Montferrier-sur-Lez, France
5Real Jardín Botánico de Madrid, CSIC (RJB-CSIC), Plaza
de Murillo 2, Madrid 28014, Spain
6Department of Ecology and Evolutionary Biology,
University of Arizona, PO Box 210088, Tucson, AZ 85721, USA
7Laboratoire de Recherche sur les Zones Arides, USTHB/INA
El Harrach, Alger BP44, Algeria
8UMR CNRS 6134 SPE, LBBMV, Université de Corse, Corte
20250, France
9Royal Botanic Gardens, Kew, Richmond TW9 3DS, UK
e-mail: guillaume.besnard@univ-tlse3.fr
Received
November 28, 2012.
Accepted
January 10, 2013.
© 2013 The Author(s) Published by the
Royal Society. All rights reserved.
Abstract
The location and timing of
domestication of the olive tree, a key crop in Early Mediterranean societies,
remain hotly debated. Here, we unravel the history of wild olives (oleasters),
and then infer the primary origins of the domesticated olive. Phylogeography
and Bayesian molecular dating analyses based on plastid genome profiling of
1263 oleasters and 534 cultivated genotypes reveal three main lineages of
pre-Quaternary origin. Regional hotspots of plastid diversity, species
distribution modelling and macrofossils support the existence of three
long-term refugia; namely the Near East (including Cyprus), the Aegean area and
the Strait of Gibraltar.
These ancestral wild gene pools have provided the
essential foundations for cultivated olive breeding. Comparison of the
geographical pattern of plastid diversity between wild and cultivated olives
indicates the cradle of first domestication in the northern Levant followed by
dispersals across the Mediterranean basin in parallel with the expansion of
civilizations and human exchanges in this part of the world.
A learned Comment:
But to get a true sense of how the olive tree emerged, the researchers shouldn't just look at chloroplast DNA, said André Bervillé, a geneticist at the French National Institute for Agricultural Research, who was not involved in the study. Nuclear DNA, which is carried in the pollen, should also be analyzed, Bervillé told LiveScience.
"Pollen from the olive tree is wind-transported, so it can migrate long distances" he said.
Combining both types of DNA would allow researchers to understand both how local olive tree cultivation occurred and how more long-distance changes occurred, he said.
A learned Comment:
But to get a true sense of how the olive tree emerged, the researchers shouldn't just look at chloroplast DNA, said André Bervillé, a geneticist at the French National Institute for Agricultural Research, who was not involved in the study. Nuclear DNA, which is carried in the pollen, should also be analyzed, Bervillé told LiveScience.
"Pollen from the olive tree is wind-transported, so it can migrate long distances" he said.
Combining both types of DNA would allow researchers to understand both how local olive tree cultivation occurred and how more long-distance changes occurred, he said.
