Karyotypes, heterochromatin and physical mapping of rDNA in vine cactaceae

MORENO N; LAS PEÑAS M. L.; BERNARDELLO G.

HASELTONIA

CACTUS SUCCULENT SOC AMER INC

Lugar: Berkeley; Año: 2015 vol. 20 p. 26 - 33

1070-0048

We performed karyotype analyses in the following Hylocereineae species: Epiphyllum phyllanthus, Selenicereus aff. megalanthus and S. aff. setaceuswere diploid with 2n =22 chromosomes, whereas S. setaceus was tetraploid. Karyotypeswere symmetrical with the formulas 11 m in E. phyllanthus, S. aff. setaceus and S. aff.megalanthus, and 22 m in S. setaceus. Chromosomes were small; the average chromosome length was 2.76 μm. Diploid species had two terminal satellites; tetraploids had four terminal satellites. The only bands associated with NOR that were found in all specimens were CMA+/DAPI− bands. Pericentromeric heterochromatin was found in S. aff. megalanthus. The locations of the 18−5.8−26S rDNA sites in all species coincided with CMA+ bands. The signals of the 5S rDNA gene were located in paracentromeric regions on at least one locus in all taxa. Additional 5S loci were found in all species, with exception of E. phyllanthus. One pair of 5S sites was co-localized with 18−5.8−26S loci in S. aff. setaceus and tetraploid S. setaceus, which is a new position for the Cactaceae. The 18−5.8−26S rDNA loci seem to be highly conserved, in contrast with the 5S rDNA loci that were scattered throughout the genome.