title: AtIQM1, a novel calmodulin-binding protein, is involved in stomatal movement in Arabidopsis.
abstract: We recently identified a novel IQ motif-containing protein family, IQM, which shares sequence homology with a pea heavy metal-induced protein 6 and a ribosome inactivating protein, trichosanthin. Distinct expression patterns for each gene suggest that each IQM family member may play a different role in plant development and response to environmental cues. However functions of the IQM family members remain to be analyzed. IQM1 bound with calmodulin 5 (CaM5) in yeast two-hybrid assay via its IQ-motif. The CaM binding was Ca(2+)-independent in vitro, and was also observed in bimolecular fluorescence complementation analyses in onion epidermal cells. IQM1 was found to express strongly in guard cells and the cortex of roots. The T-DNA insertion mutants of IQM1 displayed a smaller stomatal aperture, a decreased water loss rate and a shorter primary root. Moreover, iqm1 did not change its stomatal aperture when treated with light, dark, ABA and chitin obviously. Microarray analyses showed that 243 and 28 genes were up- and down-regulated by more than twofold in iqm1-1, respectively. Interesting, 34 of 117 and 7 of 30 chitin-responsive transcriptional factor and ubiquitin ligase genes were up-regulated, respectively. Stomatal guard cells of iqm1-1 also showed enhanced expression of genes involved in production and signaling of reactive oxygen species (ROS). Consistently, increased ROS level was observed in the iqm1 guard cells.
authors.affiliation: Guangzhou Key Laboratory for Functional Study on Plant Stress-Resistant Genes, Guangzhou University, Guangzhou, 510006, China.
authors.forename: Yu-Ping
authors.initials: YP
authors.lastname: Zhou
authors.forename: Jun
authors.initials: J
authors.lastname: Duan
authors.forename: Takahiro
authors.initials: T
authors.lastname: Fujibe
authors.forename: Kotaro T
authors.initials: KT
authors.lastname: Yamamoto
authors.forename: Chang-En
authors.initials: CE
authors.lastname: Tian
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000382:microbiology / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D020013:Calcium Signaling; D002148:Calmodulin-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D002686:Chitin / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics; D005658:Fungi / Q000472:pathogenicity; D020869:Gene Expression Profiling; D017343:Genes, Plant; D009068:Movement / Q000502:physiology; D016254:Mutagenesis, Insertional; D054046:Plant Stomata / Q000235:genetics / Q000502:physiology; D054730:Protein Interaction Domains and Motifs; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction; D020798:Two-Hybrid System Techniques
chemical_list: D029681:Arabidopsis Proteins; D002148:Calmodulin-Binding Proteins; D004269:DNA, Bacterial; D017382:Reactive Oxygen Species; C036483:T-DNA; D002686:Chitin