Putrescin modulates metabolic and physiological characteristics of Thymus daenensis under drought stress

This experiment was conducted to understand the protective impact of exogenous putrescine (Put) in Thymus daenensis under drought stress. Plants of T. daenensis were subjected to drought stress (15% polyethylene glycol) and Put (0.2 mM). Drought stress lowered growth attributes and photosynthetic pigments in T. daenensis plants. The increase in the content of malondialdehyde (MDA) and hydrogen peroxide (H2O2) as oxidative stress indicators showed that drought stress caused oxidative stress in T. daenensis plants. Drought stress augmented proline content, phenylalanine ammonia-lyase activity, tyrosine ammonia-lyase activity, indole-3-acetic acid content and methyl jasmonate content in T. daenensis plants. Put treatment improved growth and regulated adaptative mechanisms in T. daenensis plants. Decrease in H2O2 and lipid peroxidation (MDA content) by Put displayed that Put helped to alleviate drought-trigged oxidative stress in T. daenensis plants. Put application strengthened the antioxidant system as a resistance response in the drought-treated T. daenensis plants thereby induction in enzymes activities (superoxide dismutase, catalase and peroxidase) and non-enzymatic antioxidants (total phenol and flavonoid). Put treatment increased coumaric acid and resveratrol content in stressed plants. These results propose a multifaceted contribution of Put on adaptative mechanisms in T. daenensis plants under drought stress.