Recent long-distance transgene flow into wild populations conforms to historical patterns of gene flow in cotton (Gossypium hirsutum) at its centre of origin

Authors

  • A. WEGIER,

    1. Instituto de Ecología, Universidad Nacional Autónoma de México, Apartado postal 70-725, CP 04510, México DF, México
    2. Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, Progreso 5, Coyoacán, 04010, México DF, México
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  • A. PIÑEYRO-NELSON,

    1. Instituto de Ecología, Universidad Nacional Autónoma de México, Apartado postal 70-725, CP 04510, México DF, México
    2. Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, Progreso 5, Coyoacán, 04010, México DF, México
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  • J. ALARCÓN,

    1. Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México, Apartado postal 70-725, CP 04510, México DF, México
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  • A. GÁLVEZ-MARISCAL,

    1. Comisión Nacional para el Conocimiento y Uso de la Biodiversidad, Liga Periférico-Insurgentes Sur 4903, Parques del Pedregal, Tlalpan 14010, México DF, México
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  • E. R. ÁLVAREZ-BUYLLA,

    1. Instituto de Ecología, Universidad Nacional Autónoma de México, Apartado postal 70-725, CP 04510, México DF, México
    2. Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, Progreso 5, Coyoacán, 04010, México DF, México
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  • D. PIÑERO

    1. Instituto de Ecología, Universidad Nacional Autónoma de México, Apartado postal 70-725, CP 04510, México DF, México
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  • Present address: CENID-COMEF, Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, Progreso 5, Coyoacán, 04010, México DF, México.

Ana Wegier, Fax: (+52 55) 36 26 87 00 Ext. 104E-mail: awegier@gmail.com

Abstract

Over 95% of the currently cultivated cotton was domesticated from Gossypium hirsutum, which originated and diversified in Mexico. Demographic and genetic studies of this species at its centre of origin and diversification are lacking, although they are critical for cotton conservation and breeding. We investigated the actual and potential distribution of wild cotton populations, as well as the contribution of historical and recent gene flow in shaping cotton genetic diversity and structure. We evaluated historical gene flow using chloroplast microsatellites and recent gene flow through the assessment of transgene presence in wild cotton populations, exploiting the fact that genetically modified cotton has been planted in the North of Mexico since 1996. Assessment of geographic structure through Bayesian spatial analysis, BAPS and Genetic Algorithm for Rule-set Production (GARP), suggests that G. hirsutum seems to conform to a metapopulation scheme, with eight distinct metapopulations. Despite evidence for long-distance gene flow, genetic variation among the metapopulations of G. hirsutum is high (He = 0.894 ± 0.01). We identified 46 different haplotypes, 78% of which are unique to a particular metapopulation, in contrast to a single haplotype detected in cotton cultivars. Recent gene flow was also detected (m = 66/270 = 0.24), with four out of eight metapopulations having transgenes. We discuss the implications of the data presented here with respect to the conservation and future breeding of cotton populations and genetic diversity at its centre of crop origin.

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