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Recent population decline and selection shape diversity of taxol-related genes

Authors

  • C. BURGARELLA,

    1. Department of Forest Ecology and Genetics, Center of Forest Research, INIA, Carretera de A Coruña km 7.5, E-28040 Madrid, Spain
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    • Present address: INRA, UMR AGAP 1334, Campus de La Gaillarde, 2 place Viala, F-34060 Montpellier, France.

  • M. NAVASCUÉS,

    1. INRA, UMR CBGP, Campus International de Baillarguet, CS 30016, F-34988 Montferrier-sur-Lez Cedex, France
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  • M. ZABAL-AGUIRRE,

    1. Department of Forest Ecology and Genetics, Center of Forest Research, INIA, Carretera de A Coruña km 7.5, E-28040 Madrid, Spain
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  • E. BERGANZO,

    1. Centro de Investigación Ecológica y Aplicaciones Forestales (CREAF), Universidad Autónoma de Barcelona, E-08193 Bellaterra, Spain
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  • M. RIBA,

    1. Centro de Investigación Ecológica y Aplicaciones Forestales (CREAF), Universidad Autónoma de Barcelona, E-08193 Bellaterra, Spain
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  • M. MAYOL,

    1. Centro de Investigación Ecológica y Aplicaciones Forestales (CREAF), Universidad Autónoma de Barcelona, E-08193 Bellaterra, Spain
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  • G. G. VENDRAMIN,

    1. Plant Genetics Institute, National Research Council, Via Madonna del Piano 10, I-50019 Sesto Fiorentino (Florence), Italy
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  • S. C. GONZÁLEZ-MARTÍNEZ

    1. Department of Forest Ecology and Genetics, Center of Forest Research, INIA, Carretera de A Coruña km 7.5, E-28040 Madrid, Spain
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Santiago C. González-Martínez, Fax: +34 913572293; E-mail: santiago@inia.es

Abstract

Taxanes are defensive metabolites produced by Taxus species (yews) and used in anticancer therapies. Despite their medical interest, patterns of natural diversity in taxane-related genes are unknown. We examined variation at five main genes of Taxus baccata in the Iberian Peninsula, a region where unique yew genetic resources are endangered. We looked at several gene features and applied complementary neutrality tests, including diversity/divergence tests, tests solely based on site frequency spectrum (SFS) and Zeng’s compound tests. To account for specific demography, microsatellite data were used to infer historical changes in population size based on an Approximate Bayesian Computation (ABC) approach. Polymorphism-divergence tests pointed to positive selection for genes TBT and TAT and balancing selection for DBAT. In addition, neutrality tests based on SFS found that while a recent reduction in population size may explain most statistics’ values, selection may still be in action in genes TBT and DBAT, at least in some populations. Molecular signatures on taxol genes suggest the action of frequent selective waves with different direction or intensity, possibly related to varying adaptive pressures produced by the host–enemy co-evolution on defence-related genes. Such natural selection processes may have produced taxane variants still undiscovered.

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