Phylogenetic analysis of Dianthus using ITS and RAPD markers reveals insights for carnation breeding

Background Carnation and Dianthus ( Dianthus spp) are globally cultivated as a cut flower, yet high summer temperatures in Taiwan significantly reduce the yield and quality of commercial cultivars. To enhance stress tolerance traits such as heat resistance and disease resistance, interspecific and intergeneric hybridization with native species is a viable approach. Since the success of hybridization is influenced by genetic distance, this study aimed to clarify the phylogenetic relationships among native species, commercial cultivars, and interspecific hybrids using internal transcribed spacer (ITS) and random amplified polymorphic DNA (RAPD) markers. Results Phylogenetic analysis based on RAPD markers effectively differentiated among native Taiwanese species, commercial varieties, interspecific hybrids, and outgroup taxa. ITS markers, on the other hand, were more informative for identifying parent-offspring relationships. Notably, Dianthus superbus var. longicalycinus from Taiwan and Japan, despite sharing the same scientific name, exhibited clear distinctions in both morphological traits and molecular profiles. Conclusions The combined use of RAPD and ITS markers provides complementary insights into the genetic relationships within the Dianthus genus. These findings not only support the strategic use of molecular markers in breeding programs but also highlight the need to reassess taxonomic classifications among morphologically similar varieties. This study provides genetics, breeding tools, and germplasm information for future Dianthus breeding.