Chromosomal polymorphism of Calendula officinalis revealed by molecular cytogenetic markers

In karyotypes of Calendula officinalis L. (Asteraceae) (2n = 32) from various ecological and geographical places of growth, intraspecific polymorphism was studied based on patterns of chromosomal localization of molecular cytogenetic markers: C/DAPI bands and also 45S and 5S rDNA clusters. In all calendula samples, variable C/DAPI bands were found in the proximal-median regions of chromosomes. FISH revealed similar localization on chromosomes of the main 45S and 5S rDNA clusters: 45S rDNA clusters were localized on chromosomes 1 and 9, and 5S rDNA cluster was detected on the long arm of chromosome 10. Additionally, minor sites of 45S rDNA were identified in the karyotypes of calendula samples from Crimea and Belarus. Intraspecific variability in number and location of the minor 45S rDNA sites was revealed on chromosomes of C. officinalis plants from different places of growth. © 2025 Elsevier B.V., All rights reserved.