Chromosome characterization and genome size in Nigella and Garidella species (Ranunculaceae) with their taxonomic implications

Detailed karyological analyses of the Nigelleae tribe which includes taxa belonging to both genera Garidella and Nigella were performed. All studied taxa are diploid with 2 n = 12 and all the chromosomes are Ranunculus-type, chromosome size is large, and all taxa exhibit metacentric chromosomes. The karyotype formulas for Nigella and Garidella are 10m+2st and 12m, respectively, and only Nigella orientalis has satellite (SAT) chromosomes among the studied taxa. Secondary constrictions were documented in N. elata and N. orientalis . Genome size was determined using flow cytometry (FCM) and 2C genome sizes of some diploid Nigella species ranged from 21.25 to 23.48 pg. In contrast, a much smaller genome size, 17.68 pg, was determined in Garidella nigellastrum . UPGM cluster analyses were carried out to evaluate the correspondence between chromosomal features and the taxonomy of the tribe. The results showed that karyological parameters are highly useful in taxonomic delimitation at the generic level.