Comparative karyotype analysis of eleven species of Lilium from China using FISH with rDNA oligo-probes

The complexity of the classification of the genus Lilium necessitates further molecular cytogenetic research to clarify the karyotype differentiation and chromosome evolution among species, validate the existing classification, and help resolve ongoing classification disputes. In this study, the chromosomes of eleven species of Lilium, encompassing main medicinal and edible lilies in China as well as seven species endemic to southwest and central China, were characterized using fluorescence in situ hybridization (FISH) with 5S and 35S rDNA oligonucleotide probes. Quantitative molecular cytogenetic karyotypes were established using the dataset of chromosome measurements and FISH signals. Karyotype asymmetry indices were calculated to assess their karyotype asymmetry and infer their karyological relationships. Karyotype structures could be differentiated through the scatter plot of MCA versus CVCL. FISH results revealed 1–2 5S rDNA loci and 2–6 35S rDNA loci across the examined species, with most 35S loci associated with secondary constrictions. Comparative analysis of rDNA patterns, combined with PCoA based on x, 2n, TCL, MCA, CVCL and CVCI provided insights into the evolutionary relationships among these species. Our findings provide cytogenetic support for the taxonomic validity of subset. Leucolirion 6a in the most recent revised classification of Lilium.