title: TOPOISOMERASE 6B is involved in chromatin remodelling associated with control of carbon partitioning into secondary metabolites and cell walls, and epidermal morphogenesis in Arabidopsis.
abstract: Plant growth is continuous and modular, a combination that allows morphogenesis by cell division and elongation and serves to facilitate adaptation to changing environments. The pleiotropic phenotypes of the harlequin (hlq) mutant, isolated on the basis of ectopic expression of the abscisic acid (ABA)- and auxin-inducible proDc3:GUS reporter gene, were previously characterized. Mutants are skotomorphogenic, have deformed and collapsed epidermal cells which accumulate callose and starch, cell walls abundant in pectins and cell wall proteins, and abnormal and reduced root hairs and leaf trichomes. hlq and two additional alleles that vary in their phenotypic severity of starch accumulation in the light and dark have been isolated, and it is shown that they are alleles of bin3/hyp6/rhl3/Topoisomerase6B. Mutants and inhibitors affecting the cell wall phenocopy several of the traits displayed in hlq. A microarray analysis was performed, and coordinated expression of physically adjacent pairs/sets of genes was observed in hlq, suggesting a direct effect on chromatin. Histones, WRKY and IAA/AUX transcription factors, aquaporins, and components of ubiquitin-E3-ligase-mediated proteolysis, and ABA or biotic stress response markers as well as proteins involved in cellular processes affecting carbon partitioning into secondary metabolites were also identified. A comparative analysis was performed of the hlq transcriptome with other previously published TopoVI mutant transcriptomes, namely bin3, bin5, and caa39 mutants, and limited concordance between data sets was found, suggesting indirect or genotype-specific effects. The results shed light on the molecular mechanisms underlying the det/cop/fus-like pleiotropic phenotypes of hlq and support a broader role for TopoVI regulation of chromatin remodelling to mediate development in response to environmental and hormonal signals.
authors.affiliation: Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409-3131, USA.
authors.forename: Amandeep
authors.initials: A
authors.lastname: Mittal
authors.affiliation: Tamil Nadu Agricultural University, Department of Plant Breeding and Genetics, Agricultural College and Research Institute, Madurai-625 104, India.
authors.forename: Rajagopal
authors.initials: R
authors.lastname: Balasubramanian
authors.affiliation: Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409-3131, USA.
authors.forename: Jin
authors.initials: J
authors.lastname: Cao
authors.affiliation: Department of Biotechnology, Guru Nanak Dev University, Amritsar-143 005, Punjab, India.
authors.forename: Prabhjeet
authors.initials: P
authors.lastname: Singh
authors.affiliation: South Dakota State University, Department of Plant Science, Brookings, SD 57007, USA.
authors.forename: Senthil
authors.initials: S
authors.lastname: Subramanian
authors.affiliation: Institute for Integrative Genome Biology, University of California, Riverside, CA 92521, USA Department of Botany and Plant Sciences, University of California, Riverside CA 92521-0124, USA.
authors.forename: Glenn
authors.initials: G
authors.lastname: Hicks
authors.affiliation: Department of Botany and Plant Sciences, University of California, Riverside CA 92521-0124, USA.
authors.forename: Eugene A
authors.initials: EA
authors.lastname: Nothnagel
authors.affiliation: Texas Tech University, Department of Plant and Soil Science and Fiber and Biopolymer Research Institute, 1001 East Loop 289, Lubbock, TX 79409-5019, USA.
authors.forename: Noureddine
authors.initials: N
authors.lastname: Abidi
authors.affiliation: University of Arizona, Department of Plant Sciences and BIO5 Institute, 341 Keating Bldg, Tucson, AZ 85721, USA.
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Janda
authors.affiliation: University of Arizona, Department of Plant Sciences and BIO5 Institute, 341 Keating Bldg, Tucson, AZ 85721, USA.
authors.forename: David W
authors.initials: DW
authors.lastname: Galbraith
authors.affiliation: Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409-3131, USA chris.rock@ttu.edu.
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Rock
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000378:metabolism; D050260:Carbohydrate Metabolism; D049108:Cell Enlargement; D002473:Cell Wall / Q000378:metabolism; D042002:Chromatin Assembly and Disassembly; D027101:DNA Topoisomerase IV / Q000378:metabolism*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D058685:Genetic Pleiotropy; D008027:Light; D009154:Mutation; D063245:Plant Development; D019441:Plant Epidermis / Q000254:growth & development; D010937:Plant Growth Regulators / Q000378:metabolism; D064210:Secondary Metabolism; D013213:Starch / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D010937:Plant Growth Regulators; D013213:Starch; D027101:DNA Topoisomerase IV
keywords: Anthocyanin; cell wall; endoreduplication; hypocotyl; light; oxidative stress; root hairless; skotomorphogenesis; starch.