Karyological study on 12 species of the genus Taraxacum (Asteraceae) grown in Turkey

Abstract

The somatic chromosomes and karyotypes of 12 Taraxacum species were determined. All studied species were collected from natural habitats in Marmara Region, NW Turkey. The chromosome numbers of Taraxacum aznavourii (2n = 24), T. gracilens (2n = 24), T. hyberniforme (2n = 32) and T. pseudobrachyglossum (2n = 24) are reported here for the first time. The basic chromosome number was found as x = 8 and all the examined taxa are triploid or tetraploid. All the examined species of the sections Erythrosperma and Palustria are triploids (2n = 3x = 24), while of the section Scariosa all are tetraploids (2n = 4x = 32), with the exception of T. minimum, which is both triploids and tetraploids. The detailed karyotype features of the 12 Taraxacum Taraxacum species are also presented.

The Nuclear 35S rDNA World in Plant Systematics and Evolution: A Primer of Cautions and Common Misconceptions in Cytogenetic Studies

“…Interestingly, these authors do not support the presence of the previously differentiated Taraxacum -type and conventional-type satellites by Mogie and Richards (1983) . Most importantly, all analyzed species showed at least one secondary constriction, refuting the view that the lack of SAT-chromosomes is a reliable karyological marker in dandelions, as previously indicated ( Mogie and Richards, 1983 ; Gürdal and Özhatay, 2018 ). However, the work of Macháčková et al (2021) raises additional questions.…”

“…Alternative, more powerful techniques (Ag-NOR, immunolocalization) are needed to locate the transcriptionally active ribosomal loci at the secondary constrictions. Terasaka and Tanaka, 1974;Gao et al, 2012;Gürdal and Özhatay, 2018 All SAT-chromosomes are satellited chromosomes SAT-chromosome is not a synonym for satellited-chromosome, but implies either a satellited chromosome or a chromosome with a secondary constriction associated with the formation of the nucleolus, which does not have a satellite. Berger, 1940 Only satellited chromosomes show NOR loci Active 35S rDNA loci may be present at the terminal ends of chromosomes.…”

“…It was suggested that such uncertainties regarding secondary constrictions might partially be explained by the experimental vagueness associated to the lack of strict uniformity of the pretreatment procedures ( Den Nijs et al, 1978 ). Despite these concerns, however, there has been an increase in the number of reports on the number, size and morphology of satellited chromosomes for taxonomic and evolutionary purposes in Taraxacum (e.g., Gürdal and Özhatay, 2018 ; Watanabe et al, 2021 ). Again, the apparent lack of secondary constrictions continues to be reported in some species ( T. scaturiginosum ) ( Gürdal and Özhatay, 2018 ).…”

“…Despite these concerns, however, there has been an increase in the number of reports on the number, size and morphology of satellited chromosomes for taxonomic and evolutionary purposes in Taraxacum (e.g., Gürdal and Özhatay, 2018 ; Watanabe et al, 2021 ). Again, the apparent lack of secondary constrictions continues to be reported in some species ( T. scaturiginosum ) ( Gürdal and Özhatay, 2018 ). A recent study investigated the position and number of 35S rDNA loci in 38 Taraxacum species covering different reproduction modes, geographical regions and putative phylogenetic groups using FISH ( Macháčková et al, 2021 ).…”