Systematics/Phytogeography / Taxonomie/ Section
Emshwiller, Eve , Theim, Terra J. , Hatas, Emily .
Application of AFLP and plastid sequence data to the question of the origins of polyploidy of Oxalis tuberosa.
Previous research aimed at understanding the origins of polyploidy and domestication of the octoploid tuber crop “oca,” Oxalis tuberosa Molina, used DNA sequence data of two nuclear loci, the internal transcribed spacer of nuclear ribosomal DNA (ITS) and the chloroplast-expressed (but nuclear-encoded) isozyme of glutamine synthetase (ncpGS). In addition, a previous comparison of AFLP data with a local vernacular classification of oca folk cultivars found marked molecular divergence between the two traditional use categories for oca: sweeter kinds for wayk’u (boiling) and sour kinds for khaya (preserved by soaking, freezing and drying). Here we compare the previous results to new data of AFLP profiles and DNA sequences of 5 plastid loci for cultivated oca and for several wild tuber-bearing populations. The wild tuber-bearing Oxalis populations appear to comprise four different taxa. Two of these taxa, O. picchensis R. Knuth of southern Peru and an as-yet-unnamed taxon of Bolivia, were included in the prior ITS and ncpGS analyses, which identified both of them as good candidates as the genome donors of octoploid oca. Two other taxa were not studied previously: O. chicligastensis R. Knuth of northwestern Argentina, and another unnamed taxon, this one of Lima department, Peru. Analysis of the AFLP data by Neighbor-Joining, PCA, and comparison of markers shared between the octoploid crop and each progenitor candidate lead to different conclusions than the previous results with ncpGS. Specifically, the new data cast doubt on the hypothesis that O. picchensis is one of the genome donors of the octoploid cultigen. The populations in Lima Department are likewise divergent from cultivated oca. On the other hand, data of both the Bolivian wild tuber-bearing taxon and O. chicligastensis fit the expectations for a progenitor of the polyploid crop, but the data are equivocal about which is the better candidate.
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1 - University of Wisconsin-Madison, Department of Botany, Birge Hall, 430 Lincoln Drive, Madison, WI, 53706, USA
2 - University of Wisconsin Madison, Department of Botany, Birge Hall, 430 Lincoln Drive, Madison, Wisconsin, 53706-1381, USA
plastid sequence data
Presentation Type: Oral Paper:Papers for Sections
Date: Tuesday, July 29th, 2008
Time: 1:30 PM