José Luis Piña-Escutia

Karyotype analysis and physical mapping of the 5S and 45S rDNA genes in Tigridia pavonia var. Dulce (Iridaceae)

Abstract Tigridia pavonia Redouté (Iridaceae) is a species with great ornamental potential of which nine different varieties are known. Among them, Tigridia pavonia var. Dulce presents the lowest seed formation. Despite this, there are no reports on cytogenetic characteristics for this variety. In the present study its karyotype was determined, and physical mapping of the 5S and 45S rDNA genes was performed by FISH. The results show that Tigridia pavonia var. Dulce exhibited a chromosomal number of 2n = 2x = 28+3B. The karyotypic formula was 26 m + 2sm + 3B. Also, physical mapping of the 5S and 45S rDNA genes was achieved by means of the FISH technique, where the 5S rDNA gene could be mapped in eight different regions, whereas the 45S rDNA gene was observed in 10 chromosome regions, of which four corresponded to secondary constrictions. The information generated can serve as a basis for future analysis of evolutionary and/or genetic improvement in the species.