ITS sequence analysis used for parent selection in Lilium lancifolium Thunb. cross-breeding

Triploid Lilium lancifolium Thunb. is an important ornamental plant of genus Lilium with substantial food and medical value. Unfortunately, it can be propagated only asexually because of its ploidy, which seriously stunts variety improvement. Combined with ITS sequence analysis, hybridization experiments were carried out to provide new information for parent selection in L. lancifolium cross-breeding. The results showed that polymorphic sites between L. lancifolium and four related varieties were concentrated in the ITS2 region, followed by the ITS1 region, and the 5.8S region was highly conserved. Genetic distances revealed that L. lancifolium was more closely related to the four related cultivars than to 13 other materials. L. lancifolium and the four related cultivars were grouped together with Lilium bulbiferum and Lilium concolor in the phylogenetic tree. Both genetic distances and the phylogenetic tree indicated that L. lancifolium and the four related cultivars were genetically closely related. Hybridization tests revealed that both L. 'Red Life' and L. 'Sweet Surrender' were able to inflate the ovaries of L. lancifolium , and hybrid seeds were obtained between L. 'Red Life' and L. lancifolium and between L. 'Sweet Surrender' and L. lancifolium . L. 'Red Velvet' failed to pollinate L. lancifolium because the former is triploid as well. Correspondingly, L. 'Tiny Padhye' and other tested wild lilies, which had farther genetic distances from L. lancifolium , were also unable to successfully pollinate this species. In conclusion, ITS sequence analysis is an efficient way to select counterparts for L. lancifolium cross-breeding from numerous lily hybrids.