Nitric oxide acts as an antioxidant and delays programmed cell death in barley aleurone layers.
Nitric oxide (NO) is a freely diffusible, gaseous free radical and an important signaling molecule in animals. In plants, NO influences aspects of growth and development, and can affect plant responses to stress. In some cases, the effects of NO are the result of its interaction with reactive oxygen species (ROS). These interactions can be cytotoxic or protective. Because gibberellin (GA)-induced programmed cell death (PCD) in barley (Hordeum vulgare cv Himalaya) aleurone layers is mediated by ROS, we examined the effects of NO donors on PCD and ROS-metabolizing enzymes in this system. NO donors delay PCD in layers treated with GA, but do not inhibit metabolism in general, or the GA-induced synthesis and secretion of alpha-amylase. alpha-Amylase secretion is stimulated slightly by NO donors. The effects of NO donors are specific for NO, because they can be blocked completely by the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide. The antioxidant butylated hydroxy toluene also slowed PCD, and these data support our hypothesis that NO is a protective antioxidant in aleurone cells. The amounts of CAT and SOD, two enzymes that metabolize ROS, are greatly reduced in aleurone layers treated with GA. Treatment with GA in the presence of NO donors delays the loss of CAT and SOD. We speculate that NO may be an endogenous modulator of PCD in barley aleurone cells.
Beligni
Maria Veronica
MV
Instituto de Investigaciones Biologicas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, 7600, Mar del Plata, Argentina.
Fath
Angelika
A
Bethke
Paul C
PC
Lamattina
Lorenzo
L
Jones
Russell L
RL
D000040:Abscisic Acid / Q000378:metabolism / Q000494:pharmacology; D000975:Antioxidants / Q000378:metabolism / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001565:Benzoates / Q000494:pharmacology; D002084:Butylated Hydroxytoluene / Q000494:pharmacology; D002374:Catalase / Q000096:biosynthesis / Q000235:genetics; D002470:Cell Survival / Q000187:drug effects; D005456:Fluorescent Dyes; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005875:Gibberellins / Q000378:metabolism / Q000494:pharmacology; D001467:Hordeum / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D007093:Imidazoles / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000378:metabolism / Q000494:pharmacology*; D009599:Nitroprusside / Q000378:metabolism / Q000494:pharmacology; D010101:Oxygen Consumption / Q000187:drug effects; D010396:Penicillamine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D011523:Protoplasts / Q000378:metabolism; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D012639:Seeds / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D013482:Superoxide Dismutase / Q000096:biosynthesis / Q000235:genetics; D000516:alpha-Amylases / Q000096:biosynthesis / Q000235:genetics
D000975:Antioxidants; D001565:Benzoates; D005456:Fluorescent Dyes; D005875:Gibberellins; D007093:Imidazoles; D020030:Nitric Oxide Donors; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; C110881:S-nitro-N-acetylpenicillamine; C079393:1,3-dihydroxy-4,4,5,5-tetramethyl-2-(4-carboxyphenyl)tetrahydroimidazole; D009599:Nitroprusside; D002084:Butylated Hydroxytoluene; D009569:Nitric Oxide; D000040:Abscisic Acid; D002374:Catalase; D013482:Superoxide Dismutase; D000516:alpha-Amylases; D010396:Penicillamine