title: Gene regulatory variation mediates flowering responses to vernalization along an altitudinal gradient in Arabidopsis.
abstract: Steep environmental gradients provide ideal settings for studies of potentially adaptive phenotypic and genetic variation in plants. The accurate timing of flowering is crucial for reproductive success and is regulated by several pathways, including the vernalization pathway. Among the numerous genes known to enable flowering in response to vernalization, the most prominent is FLOWERING LOCUS C (FLC). FLC and other genes of the vernalization pathway vary extensively among natural populations and are thus candidates for the adaptation of flowering time to environmental gradients such as altitude. We used 15 natural Arabidopsis (Arabidopsis thaliana) genotypes originating from an altitudinal gradient (800-2,700 m above sea level) in the Swiss Alps to test whether flowering time correlated with altitude under different vernalization scenarios. Additionally, we measured the expression of 12 genes of the vernalization pathway and its downstream targets. Flowering time correlated with altitude in a nonlinear manner for vernalized plants. Flowering time could be explained by the expression and regulation of the vernalization pathway, most notably by AGAMOUS LIKE19 (AGL19), FLOWERING LOCUS T (FT), and FLC. The expression of AGL19, FT, and VERNALIZATION INSENSITIVE3 was associated with altitude, and the regulation of MADS AFFECTING FLOWERING2 (MAF2) and MAF3 differed between low- and high-altitude genotypes. In conclusion, we found clinal variation across an altitudinal gradient both in flowering time and the expression and regulation of genes in the flowering time control network, often independent of FLC, suggesting that the timing of flowering may contribute to altitudinal adaptation.
authors.affiliation: Eidgenössisch Technische Hochschule Zürich, Institute of Integrative Biology, 8092 Zurich, Switzerland (L.S., M.R., N.Z., A.W.); andDepartment of Plant Biology, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, SE-75007 Uppsala, Sweden (L.H.).
authors.forename: Léonie
authors.initials: L
authors.lastname: Suter
authors.affiliation: Eidgenössisch Technische Hochschule Zürich, Institute of Integrative Biology, 8092 Zurich, Switzerland (L.S., M.R., N.Z., A.W.); andDepartment of Plant Biology, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, SE-75007 Uppsala, Sweden (L.H.).
authors.forename: Marlene
authors.initials: M
authors.lastname: Rüegg
authors.affiliation: Eidgenössisch Technische Hochschule Zürich, Institute of Integrative Biology, 8092 Zurich, Switzerland (L.S., M.R., N.Z., A.W.); andDepartment of Plant Biology, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, SE-75007 Uppsala, Sweden (L.H.).
authors.forename: Niklaus
authors.initials: N
authors.lastname: Zemp
authors.affiliation: Eidgenössisch Technische Hochschule Zürich, Institute of Integrative Biology, 8092 Zurich, Switzerland (L.S., M.R., N.Z., A.W.); andDepartment of Plant Biology, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, SE-75007 Uppsala, Sweden (L.H.).
authors.forename: Lars
authors.identifier: http://orcid.org/0000-0002-6645-1862
authors.initials: L
authors.lastname: Hennig
authors.affiliation: Eidgenössisch Technische Hochschule Zürich, Institute of Integrative Biology, 8092 Zurich, Switzerland (L.S., M.R., N.Z., A.W.); andDepartment of Plant Biology, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, SE-75007 Uppsala, Sweden (L.H.) alex.widmer@env.ethz.ch.
authors.forename: Alex
authors.identifier: http://orcid.org/0000-0001-8253-5137
authors.initials: A
authors.lastname: Widmer
mesh_terms: D000064:Acclimatization; D000531:Altitude; D017360:Arabidopsis / Q000235:genetics* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics; D004777:Environment; D035264:Flowers / Q000235:genetics* / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D005809:Genes, Regulator / Q000235:genetics*; D014644:Genetic Variation; D005838:Genotype; D010641:Phenotype; D012098:Reproduction; D013997:Time Factors
chemical_list: D029681:Arabidopsis Proteins