Silicon Enhanced Redox Homeostasis and Protein Expression to Mitigate the Salinity Stress in Rosa hybrida 'Rock Fire'

Abstract

Silicon (Si) is considered one of the most beneficial elements for plant growth and development. Its advantageous effects are visible during abiotic and biotic stresses. In this experiment, the effect of Si on redox homeostasis and protein expression was studied in Rosa hybrida 'Rock Fire.' Acclimatized plantlets were grown hydroponically under salt stress (50 mM NaCl) for 15 days with or without 0 or 1.8 mM of potassium silicate (K2SiO3). Exposure of R. hybrida 'Rock Fire' to salinity restricted root growth. The addition of Si with NaCl significantly improved fresh and dry weights of roots. The presence of Si in the nutrient solution induced the growth of root hairs during both normal and stress conditions. Under salt stress, higher lipid peroxidation and excessive accumulation of reactive oxygen species (ROS) such as superoxide (O-2 (-)) and hydrogen peroxide (H2O2) affect the redox homeostasis potential of plants. However, addition of Si decreased the content of malondialdehyde, O-2 (-), and H2O2. Detoxification of ROS was highly correlated with the enhanced activity and expression of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and guaiacol peroxidase (GPX). In addition, the two-dimensional gel electrophoresis results illustrated the improved abundance of protein on roots to overcome the salinity stress due to the addition of Si. Out of 70 spots identified, 59 proteins [except hypothetical (6%)] were functionally classified into 8 groups such as redox homeostasis/defense (15%), transcription/translation (26%), lipid metabolism (14%), signaling (13%), energy and carbohydrate metabolism (10%), transportation/metal ion-binding (7%), terpene synthesis (3%), and cell-wall regulation (6%). The observed results suggest that the substantial improvement of redox homeostasis by Si could facilitate preventive mechanism(s) to overcome the metabolic disorder emanate under salt stress.