ABSTRACT
The taxonomically challenging genus Calendula L. (Asteraceae) includes lots of medicinal species characterized by their high morphological and karyological variability. For the first time, a repeatome analysis of a valuable medicinal plant Calendula officinalis L. was carried out using high-throughput genome DNA sequencing and RepeatExplorer/TAREAN pipelines. The FISH-based visualization of the 45S rDNA, 5S rDNA, and satellite DNAs of C. officinalis was performed on the chromosomes of C. officinalis, C. stellata Cav., C. tripterocarpa Rupr., and C. arvensis L. Three satellite DNAs were demonstrated to be new molecular chromosome markers to study the karyotype structure. Karyograms of the studied species were constructed, their ploidy status was specified, and their relationships were clarified. Our results showed that the C. officinalis karyotype differed from the karyotypes of the other three species, indicating its separate position in the Calendula phylogeny. However, the presence of common repeats revealed in the genomes of all the studied species could be related to their common origin. Our findings demonstrated that C. stellata contributed its genome to allotetraploid C. tripterocarpa, and C. arvensis is an allohexaploid hybrid between C. stellata and C. tripterocarpa. At the same time, further karyotype studies of various Calendula species are required to clarify the pathways of chromosomal reorganization that occurred during speciation.
ABSTRACT
Polemonium caeruleum L. (Polemoniaceae) is a valuable medicinal herb with a wide spectrum of biological activities. Under natural conditions, the productivity of this species is rather low. In this study, colchicine-induced tetraploid plants (2n = 4x = 36) of P. caeruleum were obtained, and for the first time, their morphological and cytogenetic characterization was performed. In the tetraploid plants, raw material productivity and also the content of triterpene saponins were significantly higher than in the control diploids. The analysis of chromosome behavior at meiosis and FISH chromosome mapping of 45S and 5S rDNA generally demonstrated stability of both genomes in the tetraploid plants. Based on chromosome morphology and distribution patterns of the studied molecular cytogenetic markers, all chromosome pairs in karyotypes were identified, and chromosome karyograms and idiograms of P. caeruleum were constructed. The revealed specific microdiagnostic characteristics of P. caeruleum (strongly sinuous cells and anomocytic stomata of the leaf epidermis, and also glandular hairs along the veins) could be useful for raw material identification. In the obtained tetraploids, the predominance of large stomata on the lower leaf epidermis was determined. The studied tetraploids can be used in various breeding programs to obtain high-quality pharmaceutical raw materials of P. caeruleum.
