Cytogenetic characterization of southern South American species of Opuntia (Cactaceae-Opuntioideae)

REALINI MF,; GOTTLIEB A. M.; FONT F,; PICCA PI; POGGIO L.; GONZÁLEZ GE,

Succulent Plant Research

David Hunt

Año: 2014; p. 31 - 46

In order to contribute to the cytogenetic characterization of 14 Opuntia species from Southern South America, chromosome number, ploidy level, karyotypic parameters and heterochromatin composition were analyzed. Chromosome counts and DAPI/CMA fluorescent banding, on mitotic metaphases, were performed. In all studied species the same basic number (x=11) was found, although different ploidy levels were detected (from 2x, 2n=22 to 5x, 2n=55). In this study the chromosome number and ploidy level of O. colubrina, O. penicilligera, O. bonaeriensis, O. megapotamica and O. ventanensis was reported for the first time. Moreover previous records of chromosome number of O. schickendantzii, O. arechavaletae, O. anacantha, O. quimilo, O. discolor and O. elata were confirmed. On the other hand, O. aurantiaca, O. salmiana and O. monacantha showed different ploidy levels than previous reports. All the species showed small size metacentric (m) chromosomes, symmetrical karyotypes and 11m as basic karyotype formulae, which demonstrate their karyotypic constancy. However, interspecific variation was observed in total chromosome length per haploid genome, and intra- and interchromosomal symmetry indexes. Also, differences in the number of terminal satellites and variability in number, size, location and composition of the heterochromatic blocks were detected. Therefore, all these valuable cytological markers allow characterization of the Opuntia species here studied, and constitute a contribution to the cytogenetic knowledge of the genus.