Physiological evaluation of drought stress tolerance and recovery in Verbascum sinuatum plants treated with methyl jasmonate, salicylic acid and titanium dioxide nanoparticles

Abstract

The genus Verbascum L. (Scrophulariaceae) includes medicinal plants, which have several bioactive compounds especially saponins. The possible recovery ability of Verbascum sinuatum from drought stress conditions was assessed by using salicylic acid (SA), methyl jasmonate (MJA) and titanium dioxide nanoparticles (TiO₂NPs) as plant growth regulators (PGRs) in liquid culture media. Thirty days-old plants were exposed to different concentrations of polyethylene glycol (PEG-6000) for creating artificial drought conditions (0, −0.3, and −0.6 MPa osmotic potential) and also treated with 200 µM methyl jasmonate (MJA), 100 µM salicylic acid (SA) and 20 ppm TiO₂ nanoparticles (TiO₂NPs). Results showed that the growth parameters and the content of photosynthetic pigments decreased at higher drought level (−0.6 MPa). However, SA and TiO₂NPs alleviated the adverse effects of drought stress by increasing water stress tolerance through promotion of enzymatic and nonenzymatic antioxidant defense systems. MJA negatively affected the growth parameters and increased the content of malondialdehyde (MDA), hydrogen peroxide (H₂O₂) and total saponin and also the activity of peroxidase (POD) and polyphenol oxidase (PPO). Based on the results obtained from this study, the recovery treatments mainly affected the defense-related metabolism in Verbasum sinuatum plants.

Keywords:

• Antioxidant defense
• drought stress
• high-performance liquid chromatography
• plant growth regulators
• Verbascum sinuatum

Disclosure statement

No potential conflict of interest was reported by the authors.