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DNA barcodes for Mexican Cactaceae, plants under pressure from wild collecting

Authors

  • CHRIS YESSON,

    1. School of Biological Sciences, Lyle Tower, The University of Reading, Reading, Berkshire RG6 6AS, UK
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    • Present address: Institute of Zoology, Zoological Society of London, Regent’s Park, London, NW1 4RY, UK.

  • ROLANDO T. BÁRCENAS,

    1. Laboratorio Darwin de Sistemática Molecular y Evolución, Facultad de Ciencias Naturales, Universidad Autónoma de Querétaro, Av. de las Ciencias s/n, Juriquilla, Querétaro CP 76230, México
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  • HÉCTOR M. HERNÁNDEZ,

    1. Departamento de Botánica, Instituto de Biología, Universidad Nacional Autónoma de México, Apartado Postal 70-233, Ciudad Universitaria, 04510 Mexico City, México
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  • MARÍA De La LUZ RUIZ-MAQUEDA,

    1. Laboratorio Darwin de Sistemática Molecular y Evolución, Facultad de Ciencias Naturales, Universidad Autónoma de Querétaro, Av. de las Ciencias s/n, Juriquilla, Querétaro CP 76230, México
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  • ALBERTO PRADO,

    1. Laboratorio Darwin de Sistemática Molecular y Evolución, Facultad de Ciencias Naturales, Universidad Autónoma de Querétaro, Av. de las Ciencias s/n, Juriquilla, Querétaro CP 76230, México
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    • Present address: Department of Plant Science, McGill University, 21, 111 Lakeshore Road, Ste. Anne de Bellevue, QC H9X 3V9, Canada.

  • VÍCTOR M. RODRÍGUEZ,

    1. School of Biological Sciences, Lyle Tower, The University of Reading, Reading, Berkshire RG6 6AS, UK
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  • JULIE A. HAWKINS

    1. School of Biological Sciences, Lyle Tower, The University of Reading, Reading, Berkshire RG6 6AS, UK
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Chris Yesson, Tel.: 020 7449 6267;
E-mail: chris.yesson@ioz.ac.uk

Abstract

DNA barcodes could be a useful tool for plant conservation. Of particular importance is the ability to identify unknown plant material, such as from customs seizures of illegally collected specimens. Mexican cacti are an example of a threatened group, under pressure because of wild collection for the xeriscaping trade and private collectors. Mexican cacti also provide a taxonomically and geographically coherent group with which to test DNA barcodes. Here, we sample the matK barcode for 528 species of Cactaceae including approximately 75% of Mexican species and test the utility of the matK region for species-level identification. We find that the matK DNA barcode can be used to identify uniquely 77% of species sampled, and 79–87% of species of particular conservation importance. However, this is far below the desired rate of 95% and there are significant issues for PCR amplification because of the variability of primer sites. Additionally, we test the nuclear ITS regions for the cactus subfamily Opuntioideae and for the genus Ariocarpus (subfamily Cactoideae). We observed higher rates of variation for ITS (86% unique for Opuntioideae sampled) but a much lower PCR success, encountering significant intra-individual polymorphism in Ariocarpus precluding the use of this marker in this taxon. We conclude that the matK region should provide useful information as a DNA barcode for Cactaceae if the problems with primers can be addressed, but matK alone is not sufficiently variable to achieve species-level identification. Additional complementary regions should be investigated as ITS is shown to be unsuitable.

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