title: Abscisic acid induces ectopic outgrowth in epidermal cells through cortical microtubule reorganization in Arabidopsis thaliana.
abstract: Abscisic acid (ABA) regulates seed maturation, germination and various stress responses in plants. The roles of ABA in cellular growth and morphogenesis, however, remain to be explored. Here, we report that ABA induces the ectopic outgrowth of epidermal cells in Arabidopsis thaliana. Seedlings of A. thaliana germinated and grown in the presence of ABA developed ectopic protrusions in the epidermal cells of hypocotyls, petioles and cotyledons. One protrusion was formed in the middle of each epidermal cell. In the hypocotyl epidermis, two types of cell files are arranged alternately into non-stoma cell files and stoma cell files, ectopic protrusions being restricted to the non-stoma cell files. This suggests the presence of a difference in the degree of sensitivity to ABA or in the capacity of cells to form protrusions between the two cell files. The ectopic outgrowth was suppressed in ABA insensitive mutants, whereas it was enhanced in ABA hypersensitive mutants. Interestingly, ABA-induced ectopic outgrowth was also suppressed in mutants in which microtubule organization was compromised. Furthermore, cortical microtubules were disorganized and depolymerized by the ABA treatment. These results suggest that ABA signaling induces ectopic outgrowth in epidermal cells through microtubule reorganization.
authors.affiliation: Department of Biological Science, Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan.
authors.forename: Shogo
authors.initials: S
authors.lastname: Takatani
authors.affiliation: Institute of Plant Science and Resources, Okayama University, Kurashiki 710-0046, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Hirayama
authors.affiliation: Graduate School of Biological Science, Nara Institute of Science and Technology, Ikoma 630-0192, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Hashimoto
authors.affiliation: Department of Biological Science, Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan.
authors.forename: Taku
authors.initials: T
authors.lastname: Takahashi
authors.affiliation: Department of Biological Science, Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan.
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Motose
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism* / Q000494:pharmacology; D017360:Arabidopsis / Q000378:metabolism*; D018525:Germination / Q000187:drug effects / Q000502:physiology*; D008870:Microtubules / Q000378:metabolism*; D019441:Plant Epidermis / Q000378:metabolism*
chemical_list: D000040:Abscisic Acid