title: The IBO germination quantitative trait locus encodes a phosphatase 2C-related variant with a nonsynonymous amino acid change that interferes with abscisic acid signaling.
abstract: Natural genetic variation is crucial for adaptability of plants to different environments. Seed dormancy prevents precocious germination in unsuitable conditions and is an adaptation to a major macro-environmental parameter, the seasonal variation in temperature and day length. Here we report the isolation of IBO, a quantitative trait locus (QTL) that governs c. 30% of germination rate variance in an Arabidopsis recombinant inbred line (RIL) population derived from the parental accessions Eilenburg-0 (Eil-0) and Loch Ness-0 (Lc-0). IBO encodes an uncharacterized phosphatase 2C-related protein, but neither the Eil-0 nor the Lc-0 variant, which differ in a single amino acid, have any appreciable phosphatase activity in in vitro assays. However, we found that the amino acid change in the Lc-0 variant of the IBO protein confers reduced germination rate. Moreover, unlike the Eil-0 variant of the protein, the Lc-0 variant can interfere with the activity of the phosphatase 2C ABSCISIC ACID INSENSITIVE 1 in vitro. This suggests that the Lc-0 variant possibly interferes with abscisic acid signaling, a notion that is supported by physiological assays. Thus, we isolated an example of a QTL allele with a nonsynonymous amino acid change that might mediate local adaptation of seed germination timing.
authors.affiliation: Department of Plant Molecular Biology, University of Lausanne, Biophore Building, CH-1015, Lausanne, Switzerland.
authors.forename: Amélia
authors.initials: A
authors.lastname: Amiguet-Vercher
authors.affiliation: Department of Plant Molecular Biology, University of Lausanne, Biophore Building, CH-1015, Lausanne, Switzerland.
authors.forename: Luca
authors.initials: L
authors.lastname: Santuari
authors.affiliation: Instituto de Biologia Molecular y Celular de Plantas, Consejo Superior de Investigaciones, Cientificas-Universidad Politecnica de Valencia, ES-46022, Valencia, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Gonzalez-Guzman
authors.affiliation: Department of Plant Molecular Biology, University of Lausanne, Biophore Building, CH-1015, Lausanne, Switzerland.
authors.forename: Stephen
authors.initials: S
authors.lastname: Depuydt
authors.affiliation: Instituto de Biologia Molecular y Celular de Plantas, Consejo Superior de Investigaciones, Cientificas-Universidad Politecnica de Valencia, ES-46022, Valencia, Spain.
authors.forename: Pedro L
authors.initials: PL
authors.lastname: Rodriguez
authors.affiliation: Department of Plant Molecular Biology, University of Lausanne, Biophore Building, CH-1015, Lausanne, Switzerland.
authors.forename: Christian S
authors.initials: CS
authors.lastname: Hardtke
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D000222:Adaptation, Physiological; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000235:genetics / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D018525:Germination / Q000235:genetics*; D010749:Phosphoprotein Phosphatases / Q000235:genetics* / Q000378:metabolism; D057445:Plant Dormancy / Q000235:genetics*; D000071636:Protein Phosphatase 2C; D040641:Quantitative Trait Loci; D012639:Seeds / Q000254:growth & development; D015398:Signal Transduction
chemical_list: D000596:Amino Acids; D029681:Arabidopsis Proteins; D000040:Abscisic Acid; D010749:Phosphoprotein Phosphatases; D000071636:Protein Phosphatase 2C
keywords: Arabidopsis thaliana; IBO; REDUCED DORMANCY 5 (RDO5); abscisic acid (ABA); natural variation; phosphatase 2C (PP2C); quantitative trait locus (QTL)