Influence of Exogenously Applied Epibrassinolide and Putrescine on Protein Content, Antioxidant Enzymes and Lipid Peroxidation in Lycopersicon esculentum under Salinity Stress

Brassinosteroids (BRs) and polyamines (PAs) are widely used to overcome abiotic stresses including salinity stress (NaCl) in plants. In the present investigation, we evaluated the co-application efficacy of 24-epibrassinolide (EBR, a highly active BR) and putrescine (Put, a PA) on the NaCl stress (75 mM and 150 mM) tolerance of Lycopersicon esculentum L. cv. kuber geeta plants. A small rise in protein content was recorded under salinity stress in comparison with untreated control. The NaCl stress was found to significantly enhance the activities of guaiacol peroxidase (GPOX) and superoxide dismutase (SOD); while decline in catalase (CAT) activity was recorded when compared with the untreated control. Salinity stress both at 75 mM and 150 mM was able to cause significant membrane damage as evidenced by an increase in the level of malondialdehyde (MDA) content over untreated control. The EBR and Put co-applications were able to improve protein content in NaCl stressed plants over only NaCl stressed plants. The co-applications of EBR and Put were able to significantly enhance the activities of CAT, SOD and GPOX in L. esculentum under salinity stress (75 mM and 150 mM) when compared with NaCl stressed plants alone. Major decline in the MDA level recorded for EBR and Put co-applications under NaCl stress revealed reduced membrane damages when compared with NaCl stressed plants alone. Our findings provide evidence that EBR and Put co-applications are effective in amelioration of NaCl stress in L. esculentum. Thus co-application potential of EBR and Put may acts an eco-friendly approach towards NaCl stress mitigation in economically important crops.