title: Nitrosative responses in citrus plants exposed to six abiotic stress conditions.
abstract: Nitrosative status has emerged as a key component in plant response to abiotic stress; however, knowledge on its regulation by different environmental conditions remains unclear. The current study focused on nitrosative responses in citrus plants exposed to various abiotic stresses, including continuous light, continuous dark, heat, cold, drought and salinity. Morphological observations and physiological analysis showed that abiotic stress treatments were sensed by citrus plants. Furthermore, it was revealed that nitrosative networks are activated by environmental stress factors in citrus leaves as evidenced by increased nitrite (NO) content along with the release of NO and superoxide anion (O₂⁻) in the vascular tissues. The expression of genes potentially involved in NO production, such as NR, AOX, NADHox, NADHde, PAO and DAO, was affected by the abiotic stress treatments demonstrating that NO-derived nitrosative responses could be regulated by various pathways. In addition, S-nitrosoglutathione reductase (GSNOR) and nitrate reductase (NR) gene expression and enzymatic activity displayed significant changes in response to adverse environmental conditions, particularly cold stress. Peroxynitrite (ONOO⁻) scavenging ability of citrus plants was elicited by continuous light, dark or drought but was suppressed by salinity. In contrast, nitration levels were elevated by salinity and suppressed by continuous light or dark. Finally, S-nitrosylation patterns were enhanced by heat, cold or drought but were suppressed by dark or salinity. These results suggest that the nitrosative response of citrus plants is differentially regulated depending on the stress type and underscore the importance of nitrosative status in plant stress physiology.
authors.affiliation: Faculty of Agriculture, Aristotle University of Thessaloniki, University Campus, 54124 Thessaloniki, Greece.
authors.forename: Vasileios
authors.initials: V
authors.lastname: Ziogas
authors.forename: Georgia
authors.initials: G
authors.lastname: Tanou
authors.forename: Panagiota
authors.initials: P
authors.lastname: Filippou
authors.forename: Grigorios
authors.initials: G
authors.lastname: Diamantidis
authors.forename: Miltiadis
authors.initials: M
authors.lastname: Vasilakakis
authors.forename: Vasileios
authors.initials: V
authors.lastname: Fotopoulos
authors.forename: Athanassios
authors.initials: A
authors.lastname: Molassiotis
mesh_terms: D000445:Aldehyde Oxidoreductases / Q000235:genetics / Q000378:metabolism; D002957:Citrus / Q000502:physiology*; D058639:Cold-Shock Response; D055864:Droughts; D004798:Enzymes / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D018869:Heat-Shock Response; D008027:Light; D050901:Nitrate Reductase / Q000235:genetics; D009573:Nitrites / Q000378:metabolism*; D030421:Peroxynitrous Acid / Q000378:metabolism; D018515:Plant Leaves / Q000502:physiology; D011499:Protein Processing, Post-Translational; D054712:Salinity; D013312:Stress, Physiological; D013481:Superoxides / Q000378:metabolism
chemical_list: D004798:Enzymes; D009573:Nitrites; D013481:Superoxides; D030421:Peroxynitrous Acid; D000445:Aldehyde Oxidoreductases; C087006:formaldehyde dehydrogenase, glutathione-independent; D050901:Nitrate Reductase