title: The CKH2/PKL chromatin remodeling factor negatively regulates cytokinin responses in Arabidopsis calli.
abstract: Cytokinins promote cell division and chloroplast development in tissue culture. We previously isolated two mutants of Arabidopsis thaliana, ckh1 (cytokinin-hypersensitive 1) and ckh2, which produce rapidly growing green calli in response to lower levels of cytokinins than those found in the wild type. Here we report that the product of the CKH2 gene is PICKLE, a protein resembling the CHD3 class of SWI/SNF chromatin remodeling factors. We also show that inhibition of histone deacetylase by trichostatin A (TSA) partially substituted for cytokinins, but not for auxin, in the promotion of callus growth, indicating that chromatin remodeling and histone deacetylation are intimately related to cytokinin-induced callus growth. A microarray experiment revealed that either the ckh1 mutation or the ckh2 mutation caused hypersensitivity to cytokinins in terms of gene expression, especially of photosynthesis-related genes. The ckh1 and ckh2 mutations up-regulated nuclear-encoded genes, but not plastid-encoded genes, whereas TSA deregulated both nuclear- and plastid-encoded genes. The ckh1 ckh2 double mutant showed synergistic phenotypes: the callus grew with a green color independently of exogenous cytokinins. A yeast two-hybrid experiment showed protein interaction between CKH1/EER4/AtTAF12b and CKH2/PKL. These results suggest that CKH1/EER4/AtTAF12b and CKH2/PKL may act together on cytokinin-regulated genes.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Furuta
authors.forename: Minoru
authors.initials: M
authors.lastname: Kubo
authors.forename: Kiyomi
authors.initials: K
authors.lastname: Sano
authors.forename: Taku
authors.initials: T
authors.lastname: Demura
authors.forename: Hiroo
authors.initials: H
authors.lastname: Fukuda
authors.forename: Yao-Guang
authors.initials: YG
authors.lastname: Liu
authors.forename: Daisuke
authors.initials: D
authors.lastname: Shibata
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Kakimoto
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism; D042002:Chromatin Assembly and Disassembly / Q000187:drug effects / Q000235:genetics; D003583:Cytokinins / Q000378:metabolism*; D004265:DNA Helicases; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000187:drug effects / Q000235:genetics; D005816:Genetic Complementation Test; D006655:Histone Deacetylases / Q000187:drug effects / Q000378:metabolism; D006877:Hydroxamic Acids / Q000494:pharmacology; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D010788:Photosynthesis / Q000235:genetics; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development; D030821:Plants, Genetically Modified; D025941:Protein Interaction Mapping; D015398:Signal Transduction; D035362:Transcription Factor TFIID / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
chemical_list: D029681:Arabidopsis Proteins; D003583:Cytokinins; C525352:EER4 protein, Arabidopsis; D006877:Hydroxamic Acids; D035362:Transcription Factor TFIID; C012589:trichostatin A; D006655:Histone Deacetylases; C402442:AT2G25170 protein, Arabidopsis; D004265:DNA Helicases