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Electronic Journal of Biotechnology
Universidad Católica de Valparaíso
ISSN: 0717-3458
Vol. 11, No. 3, 2008
Bioline Code: ej08031
Full paper language: English
Document type: Research Article
Document available free of charge

Electronic Journal of Biotechnology, Vol. 11, No. 3, 2008

 en Characterization of the nuclear ribosomal DNA unit in Oxalis tuberosa check for this species in other resources (Oxalidacea) and related species
Tosto, D.S. & Hopp, H.E.


Oxalis tuberosa check for this species in other resources is an octoploid Andean tuber crop called "oca" that belongs to the worldwide distributed genus Oxalis check for this species in other resources . The genus is very heterogeneous and its systematics is still problematic. It has been proposed that O. tuberosa evolved by polyploidization of a still not defined ancestor that belongs to an alliance of species sharing the same basic chromosome number (x = 8). Nuclear rDNA units of O. tuberosa and a selected group of four related diploid species were characterised by RFLP using different restriction endonucleases and southern hybridization probes to produce a restriction map for EcoRI and BamHI. The major rDNA unit length in O. tuberosa was estimated at 10.7 kbp. As expected, restriction site variation was observed mainly in the intergenic spacer (IGS), but was also detected in coding regions. Restriction site mapping organization of the transcribed rDNA unit of O. tuberosa is very similar to O. oblongiformis. Nucleotide sequencing of a region of O. peduncularis IGS generated a complex organization pattern of repeats and subrepeats. Diploid species O. peduncularis, O. tabaconasensis and O. aff. villosula exhibited a ladder pattern that is a consequence of a 170 bp subrepeat unit indicating that these species share organization similarity and sequence homology. The variation pattern provided information to compare among diploid species, although it did not help to clarify taxonomic relationships between O. tuberosa and the putative diploid ancestors analysed in this study. Nonetheless, the RFLP pattern exhibited by O. tuberosa for the IGS region was quite unique and will be a useful tool to prospect in other related species.

Andean crops, oca, Oxalis, rDNA, RFLPs.

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