Resumo

BAUK, Karen; SANTINAQUE, Federico; LOPEZ-CARRO, Beatriz  e  LAS PENAS, M. L. Contenido de ADN y patrón de genes ribosomales en el género monotípico Stetsonia (Cactaceae). Bol. Soc. Argent. Bot. [online]. 2016, vol.51, n.2, pp.323-330. ISSN 1851-2372.

Stetsonia coryne is a tree is tree-sized plant, with large and infundibuliform flowers (12 -15 cm). It is native to the deserts of northwestern Argentina and Bolivia, and is the only species of the genus Stetsonia. The aim of this study was to characterize this species cytologically. For this, the nuclear DNA content, chromosome number, karyotype, banding patterns and location of ribosomal genes of the species was determined. The DNA content analysis revealed a mixture of nuclei with three peaks, 2C, 4C and 8C, indicating a process of endopoliploidy on the species, being this the first report for the tribe Browningieae. It presented chromosome number of 2n = 22, with a symmetrical karyotype of 22 m, with the first pair with satellite. With fluorescent chromosome banding technique, two types of bands were observed: CMA+/ DAPI- associated centromere and NOR associated. With FISH technique, we observed that 18-5.8-26S loci were consistent with CMA+/DAPI-/NORs blocks. The signal for the 5S gene is located in a centromeric region (pair 10).

Palavras-chave : Stetsonia coryne; DNA content; Endopolyploidy; Heterochromatin; Ribosomal genes.

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