Cytological Analyses of Iris ruthenica K. Gawl. (Iridaceae), an Endangered Species in Korea

Iris L. is a perennial genus comprising approximately 300 species worldwide, with the greatest number of endemic species occurring in Asia. Iris is one of the largest genera in the family Iridaceae and includes ca. 15 species native to Korea. Although chromosome number change, karyotype restructuring, and genome size variation play an important role in plant genome diversification, understanding the karyotype variation in Korean Iris species has been hampered by the wide range of base chromosome number (x = 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22) reported to date. This study documents the chromosome numbers, karyotype structure and genome size variation in Iris ruthenica K. Gawl., an endangered species in Korea obtained using classic Feulgen staining and flow cytometry. The chromosome number of all investigated plants from the nine populations was 2n = 42. All individuals studied possessed metacentric and submetacentric chromosomes. The genome size of the I. ruthenica in eight wild populations ranged from 2.39 pg/1C to 2.45 pg/1C ($2.42{\pm}0.02pg/1C$: $mean{\pm}SD$). This study provides the first report of genome size variation in Iris ruthenica in Korea. This study lays foundation for cytogenetic further analyses employing by fluorescence in situ hybridization (FISH) to better understand the chromosomal evolution in this species and in the whole genus.