title: Intertissue signal transfer of abscisic acid from vascular cells to guard cells.
abstract: Abscisic acid (ABA) is a phytohormone that responds to environmental stresses, such as water deficiency. Recent studies have shown that ABA biosynthetic enzymes are expressed in the vascular area under both nonstressed and water-stressed growth conditions. However, specific cells in the vasculature involved in ABA biosynthesis have not been identified. Here, we detected the expression of two genes encoding ABA biosynthetic enzymes, ABSCISIC ACID DEFICIENT2 and ABSCISIC ALDEHYDE OXIDASE3, in phloem companion cells in vascular tissues. Furthermore, we identified an ATP-binding cassette transporter, Arabidopsis thaliana ABCG25 (AtABCG25), expressed in the same cells. Additionally, AtABCG25-expressing Spodoptera frugiperda9 culture cells showed an ABA efflux function. Finally, we observed that enhancement of ABA biosynthesis in phloem companion cells induced guard cell responses, even under normal growth conditions. These results show that ABA is synthesized in specific cells and can be transported to target cells in different tissues.
authors: Gene Discovery Research Group, RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan.
authors: Takashi
authors: T
authors: Kuromori
authors: Eriko
authors: E
authors: Sugimoto
authors: Kazuo
authors: K
authors: Shinozaki
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D000818:Animals; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism; D001692:Biological Transport; D007553:Isotope Labeling; D009928:Organ Specificity; D010641:Phenotype; D010937:Plant Growth Regulators / Q000378:metabolism; D054046:Plant Stomata / Q000166:cytology* / Q000378:metabolism*; D018526:Plant Transpiration / Q000502:physiology; D058526:Plant Vascular Bundle / Q000166:cytology* / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D021381:Protein Transport; D061987:Sf9 Cells; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; D010937:Plant Growth Regulators; D000040:Abscisic Acid