Stimulation of defense responses of in vitro potato plants by treatment with steroid glycosides under abiotic stresses

To elucidate the biological activity of furastanol glycosides (FG) as elicitors and their possible action mechanisms, antiradical properties of these compounds and their influence on in vitro potato (Solanum tuberosum L.) plants under abiotic stresses were studied. FG stimulated adaptive responses related to the activation of guaiacol-dependent peroxidase and suppression of lipid peroxidation (POL). Under normal conditions, in 30 min after plant treatment with 4.5 μM FG, the level of POL was decreased, activities of guaiacol- and ascorbate-dependent peroxidases increased, and activities of catalase and superoxide dismutase (SOD) remained unchanged. In 3 days after treatment with FG, POL was decreased by 20–60% in the leaves and by 50% in the roots. Under stress conditions (paraquat treatment for 11 days or hypothermia for 28 days), FG treatment reduced the level of POL by 20–40% as compared to the effects of stressors alone, which indicates FG elicitor properties. Antiradical properties of FG toward the hydroxyl radical were manifested in the reaction of deoxy-D-ribose destruction in water medium (without homogenate) within the concentration range from 4.5 to 65 μM; the effects toward the oxygen anion radical were insignificant. It is suggested that FG influence on generation of reactive oxygen species mediates the stimulation of potato plant defense responses to environmental factors.