A character‐based approach in the Mexican cycads supports diverse multigene combinations for DNA barcoding |
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| Authors: | Fernando Nicolalde‐Morejón Francisco Vergara‐Silva Jorge González‐Astorga Dennis W Stevenson Andrew P Vovides Victoria Sosa |
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| Institution: | 1. Laboratorio de Genética de Poblaciones, Biología Evolutiva. Instituto de Ecología, A. C., km 2.5 Antigua Carretera a Coatepec No. 351, Xalapa 91070, Veracruz, México;2. Instituto de Investigaciones Biológicas, Universidad Veracruzana, Av. Luis Castelazo Ayala s/n, Col. Industrial ánimas, Xalapa 91190, Veracruz, México;3. Laboratorio de Sistemática Molecular (Jardín Botánico), Instituto de Biología, Universidad Nacional Autónoma de México, 3er Circuito Exterior, Ciudad Universitaria, Coyoacán 04510, México, D. F. México;4. The New York Botanical Garden, Bronx, NY 10458‐5120, USA;5. Laboratorio de Biología Evolutiva de Cycadales, Biología Evolutiva. Instituto de Ecología, A. C., km 2.5 Antigua Carretera a Coatepec No. 351, Xalapa 91070, Veracruz, México;6. Laboratorio Molecular, Biología Evolutiva. Instituto de Ecología, A. C., km 2.5 Antigua Carretera a Coatepec No. 351, Xalapa 91070, Veracruz, México |
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| Abstract: | A DNA barcoding study was conducted to determine the optimal combination of loci needed for successful species‐level molecular identification in three extant cycad genera—Ceratozamia, Dioon, and Zamia—that occur in Mexico. Based on conclusions of a previous multigene study in representative species of all genera in the Cycadales, we tested the DNA barcoding performance of seven chloroplast coding (matK, rpoB, rpoC1, and rbcL) and non‐coding (atpF/H, psbK/I, and trnH‐psbA) regions, plus sequences of the nuclear internal transcribed spacer. We analysed data under the assumptions of the “character attributes organization system” (CAOS), a character‐based approach in which species are identified through the presence of ‘DNA diagnostics’. In Ceratozamia, four chloroplast regions and one nuclear region were needed to achieve > 70% unique species identification. In contrast, the two‐gene combination atpF/H + psbK/I and the four‐gene combination atpF/H + psbK/I + rpoC1 + ITS2 were needed to reach 79% and 75% unique species identification in Dioon and Zamia, respectively. The combinations atpF/H + psbK/I and atpF/H + psbK/I + rpoC1 + ITS2 include loci previously considered by the international DNA barcoding community. However, none of the three combinations of potential DNA barcoding loci found to be optimal with a character‐based approach in the Mexican cycads coincides with the ‘core barcode’ of chloroplast markers (matK + rbcL) recently proposed for universal use in the plant kingdom. |
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