Trehalose-6-Phosphate Synthase/Phosphatase Regulates Cell Shape and Plant Architecture in Arabidopsis

• Published in: Plant physiology (Bethesda) 2008-01, Vol.146 (1), p.97-107
• Main Authors: Chary, S. Narasimha, Hicks, Glenn R, Choi, Yoon Gi, Carter, David, Raikhel, Natasha V
• Format: Article
• Language: English
• Subjects: Arabidopsis - anatomy & histology; Arabidopsis - cytology; Arabidopsis - enzymology; Arabidopsis - growth & development; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Biological and medical sciences; Cell Biology and Signal Transduction; Cell kinetics; Cell physiology; Cell Shape - physiology; Chromosome Mapping; Chromosomes, Plant; Epidermal cells; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant; Genes; Glucosyltransferases - genetics; Glucosyltransferases - metabolism; Pavements; Phenotype; Phenotypes; Phosphatases; Plant cells; Plant Leaves - growth & development; Plant Leaves - metabolism; Plant physiology and development; Plants; Point Mutation; Protein Array Analysis; Protein Structure, Tertiary; Saccharomyces cerevisiae; Seedlings; Trehalose - biosynthesis; Trichomes; Yeasts
• ISSN: 0032-0889; 1532-2548; 1532-2548
• DOI: 10.1104/pp.107.107441

The vacuole occupies most of the volume of plant cells; thus, the tonoplast marker δ-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.