Salicylic Acid [BSA]

Increased activities of enzymatic and non-enzymatic antioxidants provide a common reaction to environmental stress in most crops. To investigate the effect of foliar application of stress moderators on enzymatic and non-enzymatic antioxidant changes, field experiments were conducted as split-plot design based on a randomized complete block design with three replications in 2017 and 2018. Planting date (early and late) was considered as the main plot, and foliar applications with 50 and 100 mM of Glycine Betaine, 1 and 2 mM of salicylic acid, and 100 and 200 mu M of sodium nitroprusside, along with the control treatment, were regarded as the subplot. The results showed that the amounts of chlorophyll pigments and the levels of enzymatic antioxidants (glutathione peroxidase, ascorbate peroxidase, superoxide dismutase, catalase), and proline increased, and H2O2 level decreased with the foliar application of stress moderators. Glycine betaine and sodium nitroprusside had the lowest and highest effects on the enzymatic antioxidant activities, respectively. The analysis of the main components revealed that in the early and delay planting date, the characteristics of enzymatic antioxidants and photosynthetic properties had the greatest effects on the enhancement of tolerance to salinity stress. In general, the results of this research demonstrated that the elevated activities of enzymatic antioxidants compared to non-enzymatic ones were more effective in reducing the impacts of salinity stress. Moreover, the foliar application of sodium nitroprusside at a concentration of 100 mu M served as the most suitable moderator for augmenting the activities of enzymatic antioxidants in salinity stress conditions.

Nitric oxide (NO) regulates the deployment of a phalanx of immune responses, chief among which is the activation of a constellation of defence-related genes. However, the underlying molecular mechanisms remain largely unknown. The Arabidopsis thaliana zinc finger transcription factor (ZF-TF), S-nitrosothiol (SNO) Regulated 1 (SRG1), is a central target of NO bioactivity during plant immunity. Here we characterize the remaining members of the SRG gene family. Both SRG2 and, especially, SRG3 were positive regulators of salicylic acid-dependent plant immunity. Analysis of SRG single, double and triple mutants implied that SRG family members have additive functions in plant immunity and, surprisingly, are under reciprocal regulation. SRG2 and SRG3 localized to the nucleus and functioned as ethylene-responsive element binding factor-associated amphiphilic repression (EAR) domain-dependent transcriptional repressors: NO abolished this activity for SRG3 but not for SRG2. Consistently, loss of GSNOR function, resulting in increased (S)NO concentrations, fully suppressed the disease resistance phenotype established from SRG3 but not SRG2 overexpression. Remarkably, SRG3 but not SRG2 was S-nitrosylated in vitro and in vivo. Our findings suggest that the SRG family has separable functions in plant immunity, and, surprisingly, these ZF-TFs exhibit reciprocal regulation. It is remarkable that, through neofunctionalization, the SRG family has evolved to become differentially regulated by the key immune-related redox cue, NO.