title: Trehalose-6-phosphate synthase/phosphatase regulates cell shape and plant architecture in Arabidopsis.
abstract: The vacuole occupies most of the volume of plant cells; thus, the tonoplast marker delta-tonoplast intrinsic protein-green fluorescent protein delineates cell shape, for example, in epidermis. This permits rapid identification of mutants. Using this strategy, we identified the cell shape phenotype-1 (csp-1) mutant in Arabidopsis thaliana. Beyond an absence of lobes in pavement cells, phenotypes included reduced trichome branching, altered leaf serration and stem branching, and increased stomatal density. This result from a point mutation in AtTPS6 encoding a conserved amino-terminal domain, thought to catalyze trehalose-6-phosphate synthesis and a carboxy-terminal phosphatase domain, is catalyzing a two-step conversion to trehalose. Expression of AtTPS6 in the Saccharomyces cerevisiae mutants tps1 (encoding a synthase domain) and tps2 (encoding synthase and phosphatase domains) indicates that AtTPS6 is an active trehalose synthase. AtTPS6 fully complemented defects in csp-1. Mutations in class I genes (AtTPS1-AtTPS4) indicate a role in regulating starch storage, resistance to drought, and inflorescence architecture. Class II genes (AtTPS5-AtTPS11) encode multifunctional enzymes having synthase and phosphatase activity. We show that class II AtTPS6 regulates plant architecture, shape of epidermal pavement cells, and branching of trichomes. Thus, beyond a role in development, we demonstrate that the class II gene AtTPS6 is important for controlling cellular morphogenesis.
authors.affiliation: Center for Plant Cell Biology, Institute for Integrative Genome Biology, University of California, Riverside, CA 92521, USA.
authors.forename: S Narasimha
authors.initials: SN
authors.lastname: Chary
authors.forename: Glenn R
authors.initials: GR
authors.lastname: Hicks
authors.forename: Yoon Gi
authors.initials: YG
authors.lastname: Choi
authors.forename: David
authors.initials: D
authors.lastname: Carter
authors.forename: Natasha V
authors.initials: NV
authors.lastname: Raikhel
mesh_terms: D017360:Arabidopsis / Q000033:anatomy & histology* / Q000166:cytology / Q000201:enzymology* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism*; D048430:Cell Shape / Q000502:physiology*; D002874:Chromosome Mapping; D032461:Chromosomes, Plant; D018506:Gene Expression Regulation, Plant; D005964:Glucosyltransferases / Q000235:genetics* / Q000378:metabolism*; D010641:Phenotype; D018515:Plant Leaves / Q000254:growth & development / Q000378:metabolism; D017354:Point Mutation; D040081:Protein Array Analysis; D017434:Protein Structure, Tertiary; D014199:Trehalose / Q000096:biosynthesis
chemical_list: D029681:Arabidopsis Proteins; D014199:Trehalose; D005964:Glucosyltransferases; C513675:TPS6 protein, Arabidopsis