title: New cross talk between ROS, ABA and auxin controlling seed maturation and germination unraveled in APX6 deficient Arabidopsis seeds.
abstract: Successful execution of germination program greatly depends on the seeds' oxidative homeostasis. We recently identified new roles for the H2O2-reducing enzyme ascorbate peroxidase 6 (APX6) in germination control and seeds' stress tolerance. APX6 replaces APX1 as the dominant APX in dry seeds, and its loss-of-function results in reduced germination due to over accumulation of ROS and oxidative damage. Metabolic analyses in dry apx6 seeds, revealed altered homeostasis of primary metabolites including accumulation of TCA cycle metabolites, ABA and auxin, supporting a novel role for APX6 in regulating cellular metabolism. Increased sensitivity of apx6 mutants to ABA or IAA in germination assays indicated impaired perception of these signals. Relative suppression of ABI3 and ABI5 expression, and induction of ABI4, suggested the activation of a signaling route inhibiting germination in apx6 seeds that is independent of ABI3. Here we provide additional evidence linking ABI4 with ABA- and auxin-controlled inhibition of germination and suggest a hypothetical model for the role of APX6 in the regulation of the crosstalk between these hormones and ROS.
authors.affiliation: a The Mina and Everard Goodman Faculty of Life Sciences ; Bar-Ilan University ; Ramat-Gan , Israel.
authors.forename: Changming
authors.initials: C
authors.lastname: Chen
authors.forename: Shir
authors.initials: S
authors.lastname: Twito
authors.forename: Gad
authors.initials: G
authors.lastname: Miller
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism* / Q000494:pharmacology; D000222:Adaptation, Physiological / Q000187:drug effects; D017360:Arabidopsis / Q000187:drug effects / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism; D060387:Ascorbate Peroxidases / Q000172:deficiency* / Q000378:metabolism; D018525:Germination / Q000187:drug effects; D007210:Indoleacetic Acids / Q000378:metabolism* / Q000494:pharmacology; D008954:Models, Biological; D012639:Seeds / Q000187:drug effects / Q000254:growth & development*; D015398:Signal Transduction / Q000187:drug effects; D013312:Stress, Physiological / Q000187:drug effects; D014157:Transcription Factors / Q000378:metabolism
chemical_list: C470421:ABI4 protein, Arabidopsis; D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; D014157:Transcription Factors; D000040:Abscisic Acid; C555296:APX6 protein, Arabidopsis; D060387:Ascorbate Peroxidases
keywords: ABA; ABI3; ABI4; ABI5; APX; ROS; Seed; ascorbate peroxidase; auxin; germination; redox