Ameliorative effects of spermine against osmotic stress through antioxidants and abscisic acid changes in soybean pods and seeds

Deficiency of water in soil is one of the severe threats to reduce the crop yield. Development of resistant plants against water deficiency has been major research in sustainable agriculture. Application of polyamines is a recent approach to increase the plants acclimation to osmotic stress. This study was conducted to determine the ameliorative role of spermine (Spm) in reproductive phase of soybean during polyethylene glycol (PEG)-induced osmotic stress condition. Osmotic stress reduced the fresh weight of pods and seeds as well as protein contents; whereas exogenous application of Spm induced the enhancement of pods and seeds fresh weight and protein contents in osmotic stress condition. Nonetheless, the lipid peroxidation was higher in osmotic stress affected pods than their controls. Exogenous application of Spm alleviated the stress effects by the reduction of lipid peroxidation and significant elevation of total polyphenol, enzyme activities such as catalase and superoxide dismutase. Endogenous abscisic acid was higher in pods collected from PEG treatment. Moreover, the exposure of Spm inhibited the abscisic acid synthesis in osmotic-stressed pods. Hence, the present study suggests that external application of Spm would improve the plant reproductive health under osmotic stress condition.