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Using chloroplast DNA markers to understand Ananas and Pseudananas genetic diversity

Duval M.F., Noyer J.L., Hamon P., Buso G.S.C., Ferreira F.R., Ferreira M.E., Coppens D'Eeckenbrugge G.. 2005. In : Rebolledo Martínez Andrés (ed.), Uriza Avila Daniel E. (ed.). Proceedings of the Fourth International pineapple symposium, Veracruz, Mexico, April 16-19, 2002. Louvain : ISHS [Belgique], p. 93-107. (Acta Horticulturae, 666). International Pineapple Symposium. 4, 2002-04-16/2002-04-19, Veracruz (Mexique).

Diversity has been examined in Ananas and Pseudananas using PCR-RFLP of chloroplast DNA (cpDNA). Ninety-seven accessions representing all valid species of both genera were included in the study, and 13 accessions of other bromeliads were added to constitute, out-group and study phylogenetic relationships. Eight primers designed from cpDNA were used to generate fragments. Restriction by 18 endonucleases generated 255 variable fragments for the whole sample and 52 for Ananas and Pseudananas. Dissimilarities were calculated from the resulting matrix using the Sokal & Michener index and the Neighbour-Joining method was used to reconstruct the diversity tree. Phylogenetic reconstruction was attempted using Wagner Parsimony. Phenetic and cladistic analyses gave consistent results. Ananas and Pseudananas form a monophyletic group, in which chloroplast data allow three strongly supported sub-groups to be identified, two of which are geographically consistent. The majority of A.parguazensis accessions constitute a northern group restricted to the Rio Negro and Orinoco basins. The tetraploid Pseudananas sagenarius joins the diploid A.fritzmuelleri to constitute the southern group. The third and largest group is the most widespread, as its distribution encompasses those of the northern and southern groups, and gathers all remaining species plus some A.parguazensis and other accessions of intermediate phenotypes. A.ananassoides is dominant in this sub-group and highly variable. Its close relationship to all cultivated species supports the hypothesis of this species being the progenitor of the domesticated pineapple. The data indicate the existence of gene flow, common within this group and scarcer with both the first and second groups. Comparison of cpDNA data with genomic DNA point to the hybrid origin of A.bracteatus and support the autopolyploidy of Pseudananas. The comparison between molecular and collecting of data point to the Guyana region as the probable center of domestication of A.comosus indicates a second diversity center in the western region of the Amazon.

Mots-clés : ananas comosus; ressource génétique; variation génétique; adn; domestication; chloroplaste; pcr; rflp; espèce; phylogénie; bromeliaceae; enzyme; amérique du sud; amazonie; pseudananas

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