Genetic structure of a Lima bean base collection using allozyme markers |
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Authors: | A Maquet I Zoro Bi M Delvaux B Wathelet J-P Baudoin |
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Institution: | (1) Faculté Universitaire des Sciences Agronomiques, Unité de Phytotechnie des Régions Intertropicales, 2 Passage des Déportés, B-5030 Gembloux, Belgium E-mail: phytotrop@fsagx.ac.be, BE;(2) Faculté Universitaire des Sciences Agronomiques, Unité de Chimie Organique et Biologique, 2 Passage des Déportés, B-5030 Gembloux, Belgium, BE |
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Abstract: | Genetic diversity and structure within a Lima bean (Phaseolus lunatus L.) base collection have been evaluated using allozyme markers. The results obtained from the analysis of wild and cultivated
accessions confirm the existence of Andean and Mesoamerican gene pools characterised by specific alleles. Wild and cultivated
accessions of the same gene pool are grouped. The Andean natural populations have a very limited geographic distribution between
Ecuador and northern Peru. The Mesoamerican wild form extends from Mexico up to Argentina through the eastern side of the
Andes. Andean and Mesoamerican cultivated accessions of pantropical distribution contribute substantially to the genetic diversity
of the Lima bean base collection. Population genetic parameters, estimated from allozymes, confirmed the predominant selfing
mating system of the Lima bean. The selfing mating system, the occurrence of small populations, and low gene flow lead to
an interpopulation gene diversity (DST=0.235) higher than the intrapopulation gene diversity (HS=0.032). On the basis of the results, guidelines are given to preserve and exploit the genetic diversity of this threatened
species. The results also confirm the independent domestication of the Lima bean in at least two centres, one of which is
located at medium elevation in the western valleys of Ecuador and northern Peru.
Received: 3 June 1997 / Accepted: 17 June 1997 |
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Keywords: | Phaseolus lunatus L Genetic diversity Plant conservation Domestication Gene pool |
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