title: Aldehyde Oxidase 4 Plays a Critical Role in Delaying Silique Senescence by Catalyzing Aldehyde Detoxification.
abstract: The Arabidopsis (Arabidopsis thaliana) aldehyde oxidases are a multigene family of four oxidases (AAO1-AAO4) that oxidize a variety of aldehydes, among them abscisic aldehyde, which is oxidized to the phytohormone abscisic acid. Toxic aldehydes are generated in plants both under normal conditions and in response to stress. The detoxification of such aldehydes by oxidation is attributed to aldehyde dehydrogenases but never to aldehyde oxidases. The feasibility of the detoxification of aldehydes in siliques via oxidation by AAO4 was demonstrated, first, by its ability to efficiently oxidize an array of aromatic and aliphatic aldehydes, including the reactive carbonyl species (RCS) acrolein, hydroxyl-2-nonenal, and malondialdehyde. Next, exogenous application of several aldehydes to siliques in AAO4 knockout (KO) Arabidopsis plants induced severe tissue damage and enhanced malondialdehyde levels and senescence symptoms, but not in wild-type siliques. Furthermore, abiotic stresses such as dark and ultraviolet C irradiation caused an increase in endogenous RCS and higher expression levels of senescence marker genes, leading to premature senescence of KO siliques, whereas RCS and senescence marker levels in wild-type siliques were hardly affected. Finally, in naturally senesced KO siliques, higher endogenous RCS levels were associated with enhanced senescence molecular markers, chlorophyll degradation, and earlier seed shattering compared with the wild type. The aldehyde-dependent differential generation of superoxide and hydrogen peroxide by AAO4 and the induction of AAO4 expression by hydrogen peroxide shown here suggest a self-amplification mechanism for detoxifying additional reactive aldehydes produced during stress. Taken together, our results indicate that AAO4 plays a critical role in delaying senescence in siliques by catalyzing aldehyde detoxification.
authors.affiliation: Jacob Blaustein Institutes for Desert Research, Albert Katz Department of Dryland Biotechnologies, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel.
authors.forename: Sudhakar
authors.identifier: 0000-0001-8439-3910
authors.initials: S
authors.lastname: Srivastava
authors.affiliation: Jacob Blaustein Institutes for Desert Research, Albert Katz Department of Dryland Biotechnologies, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel.
authors.forename: Galina
authors.identifier: 0000-0003-2452-7635
authors.initials: G
authors.lastname: Brychkova
authors.affiliation: Jacob Blaustein Institutes for Desert Research, Albert Katz Department of Dryland Biotechnologies, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel.
authors.forename: Dmitry
authors.initials: D
authors.lastname: Yarmolinsky
authors.affiliation: Jacob Blaustein Institutes for Desert Research, Albert Katz Department of Dryland Biotechnologies, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel.
authors.forename: Aigerim
authors.initials: A
authors.lastname: Soltabayeva
authors.affiliation: Jacob Blaustein Institutes for Desert Research, Albert Katz Department of Dryland Biotechnologies, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel.
authors.forename: Talya
authors.initials: T
authors.lastname: Samani
authors.affiliation: Jacob Blaustein Institutes for Desert Research, Albert Katz Department of Dryland Biotechnologies, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel gizi@bgu.ac.il.
authors.forename: Moshe
authors.identifier: 0000-0003-3307-9504
authors.initials: M
authors.lastname: Sagi
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D042931:Aldehyde Oxidase / Q000235:genetics / Q000378:metabolism*; D000447:Aldehydes / Q000378:metabolism*; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001547:Benzaldehydes / Q000378:metabolism; D055162:Biocatalysis; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000528:radiation effects; D055786:Gene Knockout Techniques; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008315:Malondialdehyde / Q000378:metabolism; D016877:Oxidants / Q000378:metabolism / Q000494:pharmacology; D010084:Oxidation-Reduction; D030821:Plants, Genetically Modified; D017382:Reactive Oxygen Species / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012639:Seeds / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D013997:Time Factors; D014466:Ultraviolet Rays
chemical_list: D000447:Aldehydes; D029681:Arabidopsis Proteins; D001547:Benzaldehydes; D016877:Oxidants; D017382:Reactive Oxygen Species; D008315:Malondialdehyde; D000040:Abscisic Acid; D006861:Hydrogen Peroxide; C100058:vanillin; C467966:AAO4 protein, Arabidopsis; D042931:Aldehyde Oxidase