Ploidy estimation in Hemerocallis species and cultivars by flow cytometry

Abstract Ploidy level was estimated for nine species and 94 cultivars in the genus Hemerocallis by flow cytometry (FCM) analysis. By using parsley ( Petroselinum crispum (Mill.) Nyman ex A.W. Hill) as an internal control, the ratio of the relative fluorescence intensity (RFI) of nuclei from each Hemerocallis genotype and parsley was calculated. The values ( Hemerocallis /parsley ratio) for 103 Hemerocallis genotypes were clearly classified into three groups: 1.84–2.13 (group 1), 2.94–3.10 (group 2), and 3.74–4.26 (group 3). Since the diploid H . fulva var. littorea (2 n =22) and the triploid H . fulva var. kwanso (2 n =33) belonged to groups 1 and 2, respectively, the other Hemerocallis genotypes belonging to groups 1, 2 and 3 were considered to be di-, tri- and tetraploid, respectively. Chromosome counting in root tip cells revealed that Hemerocallis genotypes belonging to groups 1, 2 and 3 had 22, 33 and 44 chromosomes, respectively. No cytochimeras and polysomaty were observed. Thus, FCM analysis has proven useful for simple and rapid estimation of the ploidy level of Hemerocallis species and cultivars.