title: Lipid Peroxide-Derived Short-Chain Carbonyls Mediate Hydrogen Peroxide-Induced and Salt-Induced Programmed Cell Death in Plants.
abstract: Lipid peroxide-derived toxic carbonyl compounds (oxylipin carbonyls), produced downstream of reactive oxygen species (ROS), were recently revealed to mediate abiotic stress-induced damage of plants. Here, we investigated how oxylipin carbonyls cause cell death. When tobacco (Nicotiana tabacum) Bright Yellow-2 (BY-2) cells were exposed to hydrogen peroxide, several species of short-chain oxylipin carbonyls [i.e. 4-hydroxy-(E)-2-nonenal and acrolein] accumulated and the cells underwent programmed cell death (PCD), as judged based on DNA fragmentation, an increase in terminal deoxynucleotidyl transferase dUTP nick end labeling-positive nuclei, and cytoplasm retraction. These oxylipin carbonyls caused PCD in BY-2 cells and roots of tobacco and Arabidopsis (Arabidopsis thaliana). To test the possibility that oxylipin carbonyls mediate an oxidative signal to cause PCD, we performed pharmacological and genetic experiments. Carnosine and hydralazine, having distinct chemistry for scavenging carbonyls, significantly suppressed the increase in oxylipin carbonyls and blocked PCD in BY-2 cells and Arabidopsis roots, but they did not affect the levels of ROS and lipid peroxides. A transgenic tobacco line that overproduces 2-alkenal reductase, an Arabidopsis enzyme to detoxify α,β-unsaturated carbonyls, suffered less PCD in root epidermis after hydrogen peroxide or salt treatment than did the wild type, whereas the ROS level increases due to the stress treatments were not different between the lines. From these results, we conclude that oxylipin carbonyls are involved in the PCD process in oxidatively stressed cells. Our comparison of the ability of distinct carbonyls to induce PCD in BY-2 cells revealed that acrolein and 4-hydroxy-(E)-2-nonenal are the most potent carbonyls. The physiological relevance and possible mechanisms of the carbonyl-induced PCD are discussed.
authors.affiliation: United Graduate School of Agriculture, Tottori University, Tottori 680-8550, Japan (M.S.B., J.M.); andScience Research Center (J.M.) and Graduate School of Agriculture (J.M.), Yamaguchi University, Yamaguchi 753-8515, Japan.
authors.forename: Md Sanaullah
authors.initials: MS
authors.lastname: Biswas
authors.affiliation: United Graduate School of Agriculture, Tottori University, Tottori 680-8550, Japan (M.S.B., J.M.); andScience Research Center (J.M.) and Graduate School of Agriculture (J.M.), Yamaguchi University, Yamaguchi 753-8515, Japan mano@yamaguchi-u.ac.jp.
authors.forename: Jun'ichi
authors.initials: J
authors.lastname: Mano
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D017360:Arabidopsis / Q000166:cytology* / Q000187:drug effects; D002336:Carnosine / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects; D016166:Free Radical Scavengers / Q000494:pharmacology; D006830:Hydralazine / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D008054:Lipid Peroxides / Q000378:metabolism*; D054883:Oxylipins / Q000378:metabolism; D018517:Plant Roots / Q000166:cytology / Q000187:drug effects; D030821:Plants, Genetically Modified; D017382:Reactive Oxygen Species / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology*; D014026:Nicotiana / Q000166:cytology* / Q000187:drug effects
chemical_list: D016166:Free Radical Scavengers; D008054:Lipid Peroxides; D054883:Oxylipins; D017382:Reactive Oxygen Species; D006830:Hydralazine; D012965:Sodium Chloride; D002336:Carnosine; D006861:Hydrogen Peroxide