The roles of reactive carbonyl species in induction of antioxidant defence and ROS signalling in extreme halophytic model Eutrema parvulum and glycophytic model Arabidopsis thaliana

Abstract

Breakdown of lipids in cell membranes by reactive oxygen species (ROS) causes production of lipid peroxidation products such as 4-hydroxy-2-nonenal (HNE), 4-hydroxy-2-hexenal (HHE), and acrolein (ACR) which are highly electrophilic due to their α-β-unsaturated carbonyl structures and named as reactive carbonyl species (RCS). The aim of this work was to investigate if RCS can induce antioxidant defence in plants and if there is a differential response in glycophytes and halophytes under non-stress conditions. For this aim, different amount and types of RCS (0.1 μM, 1 μM, 10 μM HNE, HHE and ACR) were exogenously applied to both Arabidopsis thaliana and Eutrema parvulum, and activities of some antioxidant enzymes (SOD, CAT, POX, APX) and their isoenzymes of SOD and CAT were determined. Also, to reveal role of RCS on ROS signal transduction, NADPH oxidase (NOX) activity and expression levels of abiotic stress related RBOH genes (RBOHD, RBOHF) were measured. To further elucidate the role of RCS on regulation of ion transporters in glycophyte and halophyte plants, expressions of Na+/H+ ion exchange channels on tonoplast (Na+/H+ exchanger NHX1, NHX5) and plasma membrane (salt overly sensitive 1, SOS1) were investigated. Overall, data provided in this manuscript provided evidence for regulation of antioxidant defence enzymes and ROS signalling in plants depending on the type and concentration of the RCS. In regards of glycophyte and halophyte comparison, remarkable differences were, (i) response of A. thaliana H2O2 scavenging enzymes (CAT, POX, APX) was stronger to RCS treatment when compared to E. parvulum, (ii) NADPH oxidase mediated ROS signalling was downregulated in A. thaliana, while it was maintained in E. parvulum in response to RCS. In addition, gene expression data demonstrated that RCS treatments can induced SOS1, NHX1 and NHX5 expression depending, again, on type and concentration of RCS in the absence of salt stress. Moreover, growth data indicate that RCS treatments can mitigate negative effects of salt stress in E. parvulum, but not in A. thaliana.