title: PLASTID MOVEMENT IMPAIRED1 mediates ABA sensitivity during germination and implicates ABA in light-mediated Chloroplast movements.
abstract: The plant hormone abscisic acid (ABA) controls many aspects of plant growth and development, including seed development, germination and responses to water-deficit stress. A complex ABA signaling network integrates environmental signals including water availability and light intensity and quality to fine-tune the response to a changing environment. To further define the regulatory pathways that control water-deficit and ABA responses, we carried out a gene-trap tagging screen for water-deficit-regulated genes in Arabidopsis thaliana. This screen identified PLASTID MOVEMENT IMPAIRED1 (PMI1), a gene involved in blue-light-induced chloroplast movement, as functioning in ABA-response pathways. We provide evidence that PMI1 is involved in the regulation of seed germination by ABA, acting upstream of the intersection between ABA and low-glucose signaling pathways. Furthermore, PMI1 participates in the regulation of ABA accumulation during periods of water deficit at the seedling stage. The combined phenotypes of pmi1 mutants in chloroplast movement and ABA responses indicate that ABA signaling may modulate chloroplast motility. This result was further supported by the detection of altered chloroplast movements in the ABA mutants aba1-6, aba2-1 and abi1-1.
authors.affiliation: Department of Botany and Plant Sciences and the Center for Plant Cell Biology, University of California, Riverside, CA 92521, USA; Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA. Electronic address: mrojasp@ncsu.edu.
authors.forename: Marcela
authors.initials: M
authors.lastname: Rojas-Pierce
authors.affiliation: Department of Biology, Indiana University, Bloomington, IN 47405-3700, USA; Department of Natural Science, Dickinson State University, Dickinson, ND 58601, USA.
authors.forename: Craig W
authors.initials: CW
authors.lastname: Whippo
authors.affiliation: Department of Biology, Indiana University, Bloomington, IN 47405-3700, USA.
authors.forename: Phillip A
authors.initials: PA
authors.lastname: Davis
authors.affiliation: Department of Biology, Indiana University, Bloomington, IN 47405-3700, USA.
authors.forename: Roger P
authors.initials: RP
authors.lastname: Hangarter
authors.affiliation: Department of Botany and Plant Sciences and the Center for Plant Cell Biology, University of California, Riverside, CA 92521, USA.
authors.forename: Patricia S
authors.initials: PS
authors.lastname: Springer
mesh_terms: D000040:Abscisic Acid / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D008027:Light; D009154:Mutation; D015398:Signal Transduction / Q000235:genetics / Q000528:radiation effects*
chemical_list: D029681:Arabidopsis Proteins; D047908:Intracellular Signaling Peptides and Proteins; C507141:Pmi1 protein, Arabidopsis; D000040:Abscisic Acid
keywords: ABA; Arabidopsis; Chloroplast movement; Seed germination; Water deficit