Abstract

BLANCO, Soledad; LAS PENAS, María Laura; BERNARDELLO, Gabriel  and  STIEFKENS, Laura. Mapeo de genes ribosómicos y heterocromatina en seis especies de Lycium de sudamérica (solanaceae). Bol. Soc. Argent. Bot. [online]. 2012, vol.47, n.3-4, pp.389-399. ISSN 1851-2372.

Mapping of ribosomal genes and heterochromatin in Lycium of South America (Solanaceae). The clade Lycieae (Solanaceae) embraces 92 species, currently gathered in a single genus, Lycium. A study was conducted in six South American species of this genus, using the FISH technique for the first time in the group, in addition to the CMA/DAPI banding technique. Root tips of the following species were employed: L. boerhaviifolium (previously Grabowskia), L. bridgesii (previously Phrodus), the tetraploid L. chilense and the diploids L. cestroides, L. ciliatum and L. tenuispinosum. The basic number x=12 was confirmed. The banding technique revealed CMA⁺/DAPI^- bands associated with NORs in the first m pair in the diploid species and in the first two pairs of the tetraploid. In addition, L. tenuispinosum showed an intercalary CMA⁺/DAPI^- band, while in L. bridgesii terminal and intercalary bands were found in all chromosomes. The FISH technique showed that the 18-5.8-26S loci were consistent with CMA⁺/DAPI^-/ NORs blocks. The diploid species had always one m pair carrying 5S rDNA genes, while the tetraploid presented two pairs, consistently with its ploidy level. The diversification of the studied species was not accompanied by significant structural chromosomal rearrangements, except for L. bridgesii which is outstanding because it has a different karyotype formula and a higher heterochromatin percentage.

Keywords : CMA/DAPI banding; Fluorescent in situ hybridization; Lycium.

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