Study of chromosome and monoploid genome size in Iranian endemic populations of <i>Datura stramonium</i> and <i>D. innoxia</i>

The genus Datura, a member of the economically important Solanaceae family, comprises toxic species distributed worldwide and noted for their diverse pharmacological properties. Despite its significance, the cytogenetic characteristics of Datura remain insufficiently explored, limiting insights into its genomic organization and evolutionary dynamics. In this study, four Iranian populations: three Datura innoxia and one D. stramonium, were investigated to provide a detailed cytogenetic assessment. Karyotype analyses were performed on root tip cells, while nuclear DNA content was quantified using flow cytometry with Solanum lycopersicum cv. Stupicke serving as an internal reference standard. All populations consistently displayed a diploid chromosome number of 2n=2x=24, confirming chromosomal stability within these taxa. However, significant interpopulation variation was identified in chromosome length, ranging from 2.02 to 3.53 µm, as well as in monoploid genome size, with a mean 1Cx DNA content of 1.82 pg. These results highlight a remarkable constancy in chromosome number alongside variability in genomic DNA content, emphasizing the complex cytogenetic diversity within Datura. The study provides essential baseline data for future genetic, phylogenetic, and evolutionary research, aiding in the understanding of genome organization and species differentiation in this genus.