title: Genetic and physiological analysis of biennialism in Hyoscyamus niger.
abstract: A genetic and physiological study of biennialism in the diploid selfer Hyoscyamus niger (black henbane), an obligate long-day plant, is described. Three annual and two biennial accessions that were homozygous for their respective growth habits were selected. The early-flowering trait of two annual accessions was dominant over the late-flowering trait of the third annual accession. The late-flowering annual accession, but not the early-flowering ones, responded to vernalization. Two biennial accessions remained vegetative after more than 1 year in soil and thus had an obligate vernalization requirement. Crosses between annual and biennial accessions showed that biennialism was conferred through a single dominant gene. However, plants containing only one copy of this dominant gene were transformed from biennials into very late-flowering winter-annual plants that responded more rapidly to vernalization than biennials. Taken together, these results indicated that there were allelic differences in photoperiod-specific flowering time genes and that biennialism was a dose-dependent trait with incomplete dominance. Models for flowering time regulation in henbane involving photoperiod-, vernalization-, and most likely gibberellin-specific pathways are discussed.
authors.affiliation: Department of Biological Sciences, Marquette University, Milwaukee, WI 53233, USA. michael.schlappi@marquette.edu
authors.forename: M
authors.initials: M
authors.lastname: Schläppi
mesh_terms: D000483:Alleles; D003080:Cold Temperature; D035264:Flowers / Q000235:genetics* / Q000254:growth & development*; D018506:Gene Expression Regulation, Plant; D005799:Genes, Dominant; D017343:Genes, Plant; D032304:Hyoscyamus / Q000235:genetics* / Q000254:growth & development*; D017440:Photoperiod