Inheritance of non-obligate vernalization requirement for flowering in Lilium formosanum Wallace

Commercial potted, cut flower, and garden lily production relies on forcing vegetatively-propagated, two- or three-year-old bulbs. Chilling induces stem elongation and more controlled, timely flowering in the wild and in commercial production. Select genotypes of Lilium formosanum lack dormancy and are non-obligate-vernalization-requiring (NV) for flowering. Such NV lilies flower within one year from seed. The objective of this study was to determine the inheritance of NV within select L. formosanum. Twenty-three families were generated from nine parents (6 NV, 3 obligate-vernalization-requiring [OV]). Segregation for NV:OV fit a model for NV being controlled by two genes, hereby named VER1 and VER2. A dominant allele at either locus confers the NV phenotype. For inheritance of NV, VER1 and VER2 parallels the spring/winter flowering habit and VRN1 genes of wheat. VER2 has less penetrance than VER1, and earlier stem emergence among families segregating for VERI and VER2 suggests epistatic gene action. NV lilies flower independent of chilling and are classified as a new lily flowering group: Group V. Identifying genes conferring NV in L. formosanum lays the foundation for future work to introgress NV into fast-flowering, seed-propagated lily hybrids, aid in the study of the dormancy and vernalization pathways in lily, and gene cloning.