Karyotypes, heterochromatin, and physical mapping of 18S-26S rDNA in

M. L LAS PEÑAS, J. D. URDAMPILLETA, G. BERNARDELLO, E.FORNI MARTINS

Cytogenetic and Genome Research

Karger

Lugar: Würzburg - Alemania; Año: 2008 p. 1 - 10

1424-8581

Karyotype analyses in members of the four Cactaceae subfamilies were analyzed. Numbersand karyotype formulae obtained were: Pereskioideae = Pereskia aculeata (2n=22; 10 m + 1sm), Maihuenioideae = Maihuenia patagonica (2n=22, 9 m + 1 sm; 2n=44, 18 m + 4 sm),Opuntioideae = Cumulopuntia recurvata (2n=44; 20 m + 2 sm), Cactoideae =Acanthocalycium spiniflorum (2n=22; 10 m + 1 sm), Echinopsis tubiflora (2n=22; 10 m + 1sm), Trichocereus candicans (2n=22, 22 m). Chromosomes were small, being 2.3 μm theaverage chromosome length. Diploid species and the tetraploid C. recurvata had oneterminal satellite, whereas the remaining tetraploid species showed four satellitedchromosomes. Karyotypes were symmetrical. No CMA-/DAPI+ bands were detected, butCMA+/DAPI– bands associated with NOR were always found. Pericentromericheterochromatin was found in C. recurvata, A. spiniflorum, and the tetraploid cytotype ofM. patagonica. The locations of the 18S-26S rDNA sites in all species coincided withCMA+/DAPI- bands; the same occurred with the sizes and numbers of signals for eachspecies. This technique was applied for the first time in metaphasic chromosomes in cacti.NOR-bearing pair #1 may be homeologous in all species examined. In Cactaceae, the 18S-26S loci seem to be highly conserved