Nitric oxide synthase-like dependent NO production enhances heme oxygenase up-regulation in ultraviolet-B-irradiated soybean plants.
Heme oxygenase (HO) has antioxidant properties and is up-regulated by reactive oxygen species (ROS) in ultraviolet-B-irradiated soybean plants. This study shows that nitric oxide (NO) protects against oxidative damage and that nitric oxide synthase (NOS)-like activity is also required for HO-1 induction under UV-B radiation. Pre-treatments with sodium nitroprussiate (SNP), a NO-donor, prevented chlorophyll loss, H(2)O(2) and O(2)(*-) accumulation, and ion leakage in UV-B-treated plants. HO activity was significantly enhanced by NO and showed a positive correlation with HO-1 transcript levels. In fact, HO-1 mRNA levels were increased 2.1-fold in 0.8 mM SNP-treated plants, whereas subsequent UV-B irradiation augmented this expression up to 3.5-fold with respect to controls. This response was not observed using ferrocyanide, a SNP inactive analog, and was effectively blocked by 2-(4-carboxyphenil)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO), a specific NO-scavenger. In addition, experiments carried out in the presence of N(G)-nitro-L-arginine methyl ester (L-NAME) or tungsten, well-known inhibitors of NOS and nitrate reductase, showed that NOS is the endogenous source of NO that mediates HO-1 expression. In summary, we found that NO is involved in the signaling pathway leading to HO-1 up-regulation under UV-B, and that a balance between NO and ROS is important to trigger the antioxidant response against oxidative stress.
Santa-Cruz
Diego M
DM
Departamento de Química Biológica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Argentina.
Pacienza
Natalia A
NA
Polizio
Ariel H
AH
Balestrasse
Karina B
KB
Tomaro
Maria L
ML
Yannarelli
Gustavo G
GG
D002734:Chlorophyll / Q000032:analysis / Q000378:metabolism / Q000528:radiation effects; D006419:Heme Oxygenase (Decyclizing) / Q000378:metabolism* / Q000528:radiation effects; D006861:Hydrogen Peroxide / Q000032:analysis; D019331:NG-Nitroarginine Methyl Ester / Q000737:chemistry; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000378:metabolism* / Q000528:radiation effects; D018384:Oxidative Stress / Q000528:radiation effects; D018515:Plant Leaves / Q000737:chemistry; D017382:Reactive Oxygen Species / Q000032:analysis / Q000378:metabolism; D013025:Glycine max / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D017392:Thiobarbituric Acid Reactive Substances / Q000032:analysis; D014466:Ultraviolet Rays
D017382:Reactive Oxygen Species; D017392:Thiobarbituric Acid Reactive Substances; D002734:Chlorophyll; D009569:Nitric Oxide; D006861:Hydrogen Peroxide; D019001:Nitric Oxide Synthase; D006419:Heme Oxygenase (Decyclizing); D019331:NG-Nitroarginine Methyl Ester