Role of spermidine and spermine in alleviation of drought-induced oxidative stress and photosynthetic inhibition in Chinese dwarf cherry (Cerasus humilis) seedlings

Abstract

To investigate the effect of exogenous Spermidine (Spd) and Spermine (Spm) on drought-induced damage to seedlings of Cerasus humili, relative water content (RWC), malondialdehyde content, relative electrolyte leakage, superoxide (O2 −, SOD) generation rate, hydrogen peroxide (H2O2), endogenous polyamines (PAs), antioxidant enzymes [SOD and peroxidase (POD)] activities, PA-biosynthetic enzymes [arginine decarboxylase (ADC), ornithine decarboxylase (ODC), S-adenosylmethionine decarboxylase (SAMDC)] activities, as well as photosynthetic parameters, were measured in greenhouse cultured seedlings of C. humili. The results showed that either exogenous Spd or Spm (0.2 mM) significantly enhanced the level of RWC and prevented drought-induced lipid peroxidation. They also significantly enhanced photosynthetic capability and decreased O2 − generation rate and H2O2 content. In addition, Spd and Spm helped to maintain SOD and POD activities in C. humili seedlings subjected to water stress, suggesting that they exerted a positive effect on antioxidant systems. The contents of endogenous free putrescine, Spd and Spm were increased to different extents in water-stressed C. humili seedlings. By the end of drought treatment (21 days) with exogenous Spd or Spm, the contents of free Spd increased by 30 and 38 %, respectively, and endogenous Spm increased by 41 and 26 %, respectively, compared with water-stressed plants. Furthermore, exogenous Spd or Spm enhanced the activities of ADC, ODC, and SAMDC. The pretreatment with Spd or Spm prevents oxidative damage induced by drought, and the protective effect of Spd was found to be greater than that of Spm.