title: A genetic screen for leaf movement mutants identifies a potential role for AGAMOUS-LIKE 6 (AGL6) in circadian-clock control.
abstract: The circadian clock in plants regulates many important physiological and biological processes, including leaf movement. We have used an imaging system to genetically screen Arabidopsis seedlings for altered leaf movement with the aim of identifying a circadian clock gene. A total of 285 genes were selected from publicly available microarrays that showed an expression pattern similar to those of the Arabidopsis core oscillator genes. We subsequently isolated 42 homozygous recessive mutants and analyzed their leaf movements. We also analyzed leaf movements of activation tagging mutants that showed altered flowering time. We found that agl6-1D plants, in which AGAMOUS-LIKE 6 (AGL6) was activated by the 35S enhancer, showed a shortened period of leaf movement as well as a high level of ZEITLUPE (ZTL) expression, reduced amplitude of LATE ELONGATED HYPOCOTYL (LHY) expression, and arrhythmic TIMING OF CAB EXPRESSION1 (TOC1)/CIRCADIAN CLOCK ASSOCIATED1 (CCA1) expression. A shortened period of leaf movement was also seen in 35S-AGL6-myc plants, although 35S-amiRAGL6 plants, transgenic plants overexpressing an artificial miRNA (amiR) targeting AGL6, showed unaltered leaf movement. The amplitude of CHLOROPHYLL A/B BINDING PROTEIN 2 (CAB2) expression, a circadian output gene, was also reduced in agl6-1D plants. Taken together, these results suggest that AGL6 plays a potential role in the regulation of the circadian clock by regulating ZTL mRNA level in Arabidopsis.
authors.affiliation: Creative Research Initiatives, School of Life Sciences and Biotechnology, Korea University, Seoul, 136-701, Korea.
authors.forename: Seung Kwan
authors.initials: SK
authors.lastname: Yoo
authors.forename: Sung Myun
authors.initials: SM
authors.lastname: Hong
authors.forename: Jong Seob
authors.initials: JS
authors.lastname: Lee
authors.forename: Ji Hoon
authors.initials: JH
authors.lastname: Ahn
mesh_terms: D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D057906:Circadian Clocks; D004269:DNA, Bacterial / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D045342:Light-Harvesting Protein Complexes / Q000235:genetics; D009068:Movement; D016254:Mutagenesis, Insertional; D056950:Period Circadian Proteins / Q000235:genetics* / Q000378:metabolism; D010641:Phenotype; D018515:Plant Leaves / Q000235:genetics / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics; D014158:Transcription, Genetic; D015533:Transcriptional Activation
chemical_list: C561291:AGL6 protein, Arabidopsis; D029681:Arabidopsis Proteins; C423618:CAB2 protein, Arabidopsis; C114425:CCA1 protein, Arabidopsis; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; C113192:LHY protein, Arabidopsis; D045342:Light-Harvesting Protein Complexes; D056950:Period Circadian Proteins; C036483:T-DNA; C411822:TOC1 protein, Arabidopsis; D014157:Transcription Factors; C410503:ZTL protein, Arabidopsis