KARYOTYPE DETERMINATION IN NATIVE HELICONIAS OF MEXICO

Abstract

Heliconia is a genus that groups tropical and subtropical species, and it is distributed naturally from Brazil to Mexico. The brightness of its inflorescence allows its use for ornamental purposes. Karyological studies in Heliconia report species with 2n = 2x = 22, 2n = 2x = 24 and 2n = 3x = 36 chromosomes. Because the number and chromosome morphology of Mexican species is unknown, this study aimed to determine the karyotype of Heliconia uxpanapensis, endemic to Mexico, H. latispatha, and H. stricta cv. Iris. Pretreatment of roots was performed with a physical medium (4 ± 1 ºC). The length of the haploid genome of each species was 22.21 μm for H. uxpanapensis, 26.56 μm for H. latispatha, and 25.37 μm for H. stricta. The three species have 2n = 2x = 24 chromosomes; the karyotypic formula of H. uxpanapensis is represented by 2n = 8m + 10sm (2sat) + 6st; the one for H. latispatha is 2n = 4m + 14sm + 6st (2sat); and that for H. stricta is 2n = 16m + 8sm. The first and second pairs of chromosomes of H. latispatha and H. uxpanapensis, respectively, present satellites, whereas in H. stricta the presence of the satellite was only observed in a single chromosome of the genome. This is the first study in the genus Heliconia that reports the presence of sub-telocentric chromosomes.