Abstract :
Withania somnifera, a multipurpose medicinal plant of the Himalayan region possesses antioxidant,
antitumor, anti-inflammatory, antistress, immunomodulatory, hematopoetic, anti-ageing, anxiolytic, anti-depressive
rejuvenating properties and influence various neurotransmitter receptors in the central nervous system. Withanolides,
secondary metabolites present in W. somnifera, have neuron regenerative property. In order to evaluate heat stress
mediated morphological, physiochemical, oxidative stress and antioxidant defence in the Withania somnifera, plant
was subjected to varied temperature conditions. For temperature treatments the seedlings were exposed to five
temperature conditions (8ËšC, 18ËšC, 38 ËšC, 48ËšC and 58ËšC). Seedlings grown at 22ËšC were treated as control plants.
Temperature treatments caused significant decrease in stem length, root length, fresh weight and dry weight in all
the treatments. Changes in leaf area, membrane stability and relative water content was also observed and these
protein, carotenoids, tocopherol, ascorbic acid and alkaloids decreased. The antioxidant enzymes like superoxide
dismutase, catalase, peroxidase, ascorbate peroxidase, glutathione–S-transferase, DPPH (1, 1-diphenyl-2-
picrylhydrazyl) and ABTS (2, 2’-azino-bis-3ethyl benzthiazoline-6-sulphonic acid) enhanced due to stress
treatments. Withanolides were found to be higher in high temperature treated plants. W. somnifera was found to have
protective mechanism against oxidative damage by maintaining higher enzymatic and non-enzymatic antioxidants.
Keyword :
Temperature stress, secondary metabolites, withanolides, Withania somnifera.