title: Mechanical wounding induces a nitrosative stress by down-regulation of GSNO reductase and an increase in S-nitrosothiols in sunflower (Helianthus annuus) seedlings.
abstract: Nitric oxide (NO) and related molecules such as peroxynitrite, S-nitrosoglutathione (GSNO), and nitrotyrosine, among others, are involved in physiological processes as well in the mechanisms of response to stress conditions. In sunflower seedlings exposed to five different adverse environmental conditions (low temperature, mechanical wounding, high light intensity, continuous light, and continuous darkness), key components of the metabolism of reactive nitrogen species (RNS) and reactive oxygen species (ROS), including the enzyme activities L-arginine-dependent nitric oxide synthase (NOS), S-nitrosogluthathione reductase (GSNOR), nitrate reductase (NR), catalase, and superoxide dismutase, the content of lipid hydroperoxide, hydrogen peroxide, S-nitrosothiols (SNOs), the cellular level of NO, GSNO, and GSNOR, and protein tyrosine nitration [nitrotyrosine (NO(2)-Tyr)] were analysed. Among the stress conditions studied, mechanical wounding was the only one that caused a down-regulation of NOS and GSNOR activities, which in turn provoked an accumulation of SNOs. The analyses of the cellular content of NO, GSNO, GSNOR, and NO(2)-Tyr by confocal laser scanning microscopy confirmed these biochemical data. Therefore, it is proposed that mechanical wounding triggers the accumulation of SNOs, specifically GSNO, due to a down-regulation of GSNOR activity, while NO(2)-Tyr increases. Consequently a process of nitrosative stress is induced in sunflower seedlings and SNOs constitute a new wound signal in plants.
authors.affiliation: Grupo de Señalización Molecular y Sistemas Antioxidantes en Plantas, Unidad Asociada al CSIC (EEZ), Departamento de Bioquímica y Biología Molecular, Universidad de Jaén, Spain.
authors.forename: Mounira
authors.initials: M
authors.lastname: Chaki
authors.forename: Raquel
authors.initials: R
authors.lastname: Valderrama
authors.forename: Ana M
authors.initials: AM
authors.lastname: Fernández-Ocaña
authors.forename: Alfonso
authors.initials: A
authors.lastname: Carreras
authors.forename: Maria V
authors.initials: MV
authors.lastname: Gómez-Rodríguez
authors.forename: José R
authors.initials: JR
authors.lastname: Pedrajas
authors.forename: Juan C
authors.initials: JC
authors.lastname: Begara-Morales
authors.forename: Beatriz
authors.initials: B
authors.lastname: Sánchez-Calvo
authors.forename: Francisco
authors.initials: F
authors.lastname: Luque
authors.forename: Marina
authors.initials: M
authors.lastname: Leterrier
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Corpas
authors.forename: Juan B
authors.initials: JB
authors.lastname: Barroso
mesh_terms: D000445:Aldehyde Oxidoreductases / Q000378:metabolism*; D003080:Cold Temperature; D018506:Gene Expression Regulation, Plant; D006368:Helianthus / Q000201:enzymology*; D006706:Homeostasis; D006861:Hydrogen Peroxide / Q000378:metabolism; D018546:Hypocotyl / Q000201:enzymology; D008027:Light; D050901:Nitrate Reductase / Q000378:metabolism; D009566:Nitrates / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism; D026361:Reactive Nitrogen Species / Q000378:metabolism*; D026403:S-Nitrosothiols / Q000378:metabolism*; D013314:Stress, Mechanical; D013312:Stress, Physiological
chemical_list: D009566:Nitrates; D009573:Nitrites; D026361:Reactive Nitrogen Species; D026403:S-Nitrosothiols; D009569:Nitric Oxide; D006861:Hydrogen Peroxide; D000445:Aldehyde Oxidoreductases; C087006:formaldehyde dehydrogenase, glutathione-independent; D050901:Nitrate Reductase