Chromosome markers confirm origin of Heliconia hybrids and triploids

Abstract

Heliconia L., the only genus in the Heliconiaceae family, comprises about 380 species with high ornamental potential. However, the identification of genotypes—mainly based on morphological characteristics—has generated synonyms. Therefore, it becomes necessary to apply novel techniques to differentiate genotypes and elucidate the origin of hybrids and triploids. The aim of the present work was the cytogenetic characterization of 18 Heliconia genotypes, including three hybrids, two triploids and their possible parent plants, by means of chromosome counting, staining with the fluorochromes CMA and DAPI, and FISH for 45S and 5S rDNA sites. The analyses revealed 16 diploid (2n = 2x = 24) and two triploid genotypes (2n = 3x = 36), with new counts for eight genotypes, including the triploid ‘Suriname Sassy’. The karyotypes were symmetric, with chromosomes varying from 0.88 to 3.35 µm. Regarding the CMA/DAPI staining and FISH, one CMA+/DAPI0/5S rDNA band was observed in the proximal region of two and three small chromosomes in the diploid and triploid genotypes, respectively. The CMA++/DAPI−/45S rDNA markings varied from two to four sites per genotype, revealing some interesting heteromorphisms. The distribution of 5S and 45S rDNA sites, both CMA-positive, corroborated the origin of the triploid genotypes ‘Sassy’ and ‘Suriname Sassy’ from diploid genotypes of H. psittacorum, as well as the origin of the hybrids of H. psittacorum × H. spathocircinata (‘Golden Torch’ and ‘Golden Torch Adrian’) and H. caribaea × H. bihai cv. ‘Jacquinii’ from their respective parent species.