Estimation of Genome Size Variation in Hibiscus rosa-sinensis

Tropical hibiscus ( Hibiscus rosa-sinensis L.) is a popular ornamental crop because of its abundant flower color and robust flowering ability. Extensive breeding efforts have produced numerous tropical hibiscus cultivars, thus significantly contributing to the ornamental plant industry. However, limited genetic information is available for this crop, thereby posing challenges to the development of new cultivars. This study aimed to assess the genome size variation of 96 tropical hibiscus accessions using flow cytometry. Root tissue yielded more reliable results than leaf tissue for flow cytometric analyses of this crop. The genome size evaluation unveiled a wide spectrum of genetic diversity within tropical hibiscus that ranged from 3.06 Gbp (‘Queen Aussie’) to 12.75 Gbp (‘Joanne’). Among the accessions, eight exhibited small genome sizes less than 4.2 Gbp, while three accessions possessed significantly large genomes more than 11 Gbp. The remaining 85 accessions had genome sizes that ranged from 6 to 10 Gbp. In addition, F1 hybrids were generated with greater success when parents had comparable genome size. The findings of this study provide valuable insights into the genetic diversity, offer a foundation for future breeding efforts, and directly support the genomic advancement of tropical hibiscus.