title: ABA inhibits entry into stomatal-lineage development in Arabidopsis leaves.
abstract: The number and density of stomata are controlled by endogenous and environmental factors. Despite recent advances in our understanding of stomatal development, mechanisms which prevent stomatal-lineage entry remain unclear. Here, we propose that abscisic acid (ABA), a phytohormone known to induce stomatal closure, limits initiation of stomatal development and induces enlargement of pavement cells in Arabidopsis cotyledons. An ABA-deficient aba2-2 mutant had an increased number/proportion of stomata within a smaller cotyledon, as well as reduced expansion of pavement cells. This tendency was reversed after ABA application or in an ABA over-accumulating cyp707a1cyp707a3 doublemutant. Our time course analysis revealed that aba2-2 shows prolonged formation of meristemoids and guard mother cells, both precursors of stoma. This finding is in accordance with prolonged gene expression of SPCH and MUTE, master regulators for stomatal formation, indicating that ABA acts upstream of these genes. Only aba2-2 mute, but not aba2-2 spch double mutant showed additive phenotypes and displayed inhibition of pavement cell enlargement with increased meristemoid number, indicating that ABA action on pavement cell expansion requires the presence of stomatal-lineage cells.
authors: RIKEN Plant Science Center, Tsurumi-ku, Yokohama 230-0045, Japan. Yoko.Tanaka@unige.ch
authors: Yoko
authors: Y
authors: Tanaka
authors: Tomoe
authors: T
authors: Nose
authors: Yusuke
authors: Y
authors: Jikumaru
authors: Yuji
authors: Y
authors: Kamiya
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism / Q000494:pharmacology*; D017360:Arabidopsis / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism; D049108:Cell Enlargement; D018548:Cotyledon / Q000235:genetics / Q000378:metabolism; D062951:Endoreduplication; D018506:Gene Expression Regulation, Plant; D009154:Mutation; D010641:Phenotype; D059828:Plant Cells / Q000187:drug effects / Q000378:metabolism; D018515:Plant Leaves / Q000033:anatomy & histology / Q000187:drug effects / Q000378:metabolism; D054046:Plant Stomata / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism
chemical_list: D000040:Abscisic Acid; D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; C517479:MUTE protein, Arabidopsis; C517480:SPEECHLESS protein, Arabidopsis