title: The gain-of-function Arabidopsis acd6 mutant reveals novel regulation and function of the salicylic acid signaling pathway in controlling cell death, defenses, and cell growth.
abstract: We isolated a dominant gain-of-function Arabidopsis mutant, accelerated cell death 6 (acd6), with elevated defenses, patches of dead and enlarged cells, reduced stature, and increased resistance to Pseudomonas syringae. The acd6-conferred phenotypes are suppressed by removing a key signaling molecule, salicylic acid (SA), by using the nahG transgene, which encodes SA hydroxylase. This suppression includes phenotypes that are not induced by application of SA to wild-type plants, indicating that SA acts with a second signal to cause many acd6-conferred phenotypes. acd6-nahG plants show hyperactivation of all acd6-conferred phenotypes after treatment with a synthetic inducer of the SA pathway, benzo(1,2, 3)thiadiazole-7-carbothioic acid (BTH), suggesting that SA acts with and also modulates the levels and/or activity of the second defense signal. acd6 acts partially through a NONEXPRESSOR OF PR 1 (NPR1) gene-independent pathway that activates defenses and confers resistance to P. syringae. Surprisingly, BTH-treated acd6-nahG plants develop many tumor-like abnormal growths, indicating a possible role for SA in modulating cell growth.
authors.affiliation: Chemistry and Biochemistry Graduate Program, University of Colorado at Boulder, Boulder, Colorado 80309, USA.
authors.forename: D N
authors.initials: DN
authors.lastname: Rate
authors.forename: J V
authors.initials: JV
authors.lastname: Cuenca
authors.forename: G R
authors.initials: GR
authors.lastname: Bowman
authors.forename: D S
authors.initials: DS
authors.lastname: Guttman
authors.forename: J T
authors.initials: JT
authors.lastname: Greenberg
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins; D001483:Base Sequence; D016923:Cell Death / Q000235:genetics; D002455:Cell Division / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D017343:Genes, Plant; D008954:Models, Biological; D009154:Mutation; D010641:Phenotype; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D011549:Pseudomonas / Q000472:pathogenicity; D020156:Salicylic Acid / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D014774:Virulence
chemical_list: D029681:Arabidopsis Proteins; D017931:DNA Primers; C105496:NPR1 protein, Arabidopsis; D010940:Plant Proteins; D020156:Salicylic Acid