title: Ethylene promotes germination of Arabidopsis seed under salinity by decreasing reactive oxygen species: evidence for the involvement of nitric oxide simulated by sodium nitroprusside.
abstract: Both ethylene and nitric oxide (NO) are involved in modulating seed germination in adverse environments. However, the mechanisms by which they interact and affect germination have not been explained. In this study, the relationship between ethylene and NO during germination of Arabidopsis seed under salinity was analysed. Application of exogenous 1-aminocyclopropane-1-carboxylate (ACC, a precursor of ethylene biosynthesis) or sodium nitroprusside (SNP, an NO donor) largely overcame the inhibition of germination induced by salinity. The effects of ACC and SNP were decreased by 2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide (cPTIO), a specific NO scavenger, or by aminoisobutyric acid (AIB), an inhibitor of ethylene biosynthesis, indicating that ethylene and NO interact during germination under salinity. Further, we demonstrated that ACC increased NO production and that SNP greatly induced the expression of the ACS2 gene involved in ethylene synthesis in Arabidopsis seeds germinating under salinity stress, suggesting that each substance influences the production of the other. Application of exogenous ACC increased germination under oxidative stress induced by hydrogen peroxide (H2O2) while SNP had a much smaller effect on wild-type Arabidopsis (Col-0) and no effect on the ethylene insensitive mutant (ein3-1) seeds, respectively. This shows that NO increased germination under salinity indirectly through H2O2 acting via the ethylene pathway. The endogenous concentration of H2O2 was increased by salinity in germinating seeds but was decreased by exogenous ACC, which stimulated germination ultimately. To explain all these results and the regulation of germination of Arabidopsis seed under salinity we propose a model involving ethylene, NO and H2O2 interaction.
authors.affiliation: Key Laboratory of Plant Ecology, Northeast Forestry University, Harbin 150040, China.
authors.forename: Yingchao
authors.initials: Y
authors.lastname: Lin
authors.forename: Lei
authors.initials: L
authors.lastname: Yang
authors.forename: Matthew
authors.initials: M
authors.lastname: Paul
authors.forename: Yuangang
authors.initials: Y
authors.lastname: Zu
authors.forename: Zhonghua
authors.initials: Z
authors.lastname: Tang
mesh_terms: D000598:Amino Acids, Cyclic / Q000494:pharmacology; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism* / Q000502:physiology; D003497:Cyclic N-Oxides / Q000494:pharmacology; D005030:Ethylenes / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects; D017343:Genes, Plant; D018525:Germination / Q000502:physiology*; D006861:Hydrogen Peroxide / Q000378:metabolism; D007093:Imidazoles / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D009599:Nitroprusside / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D054712:Salinity; D055049:Salt Tolerance / Q000235:genetics; D012639:Seeds / Q000187:drug effects / Q000378:metabolism*
chemical_list: D000598:Amino Acids, Cyclic; D003497:Cyclic N-Oxides; D005030:Ethylenes; D007093:Imidazoles; D010940:Plant Proteins; D009599:Nitroprusside; C079391:2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; D009569:Nitric Oxide; C023863:1-aminocyclopropane-1-carboxylic acid; C036216:ethylene; D006861:Hydrogen Peroxide
keywords: 1-aminocyclopropane-1-carboxylic acid; 2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide; ABA; ACC; ACC synthase; ACS; AIB; Arabidopsis; Col; Columbia; ETH; Ethylene; GA; H(2)O(2); Hydrogen peroxide; NO; Nitric oxide; ROS; SNP; Salinity; Seed germination; abscisic acid; aminoisobutyric acid; cPTIO; ethephon; gibberellic acid; hydrogen peroxide; nitric oxide; qRT-PCR; quantitative real time-PCR; reactive oxygen species; sodium nitroprusside