Improvement of Polyethylene Glycol, Sorbitol, Mannitol, and Sucrose-Induced Osmotic Stress Tolerance through Modulation of the Polyamines, Proteins, and Superoxide Dismutase Activity in Potato

The present study was planned to investigate the changes in morphological and biochemical parameters of in vitro-grown potato (cultivar Cardinal and Desiree) plants under osmotic stress conditions induced by various concentrations of sorbitol, mannitol (0, 0.025, 0.05, 0.10, or 0.15 M), sucrose (0, 2, 3, 4, 6, and 8%), and polyethylene glycol (PEG: MW-4000: 0, 5, 10, 15, and 20%). Nodal segments (ca. 1.0 cm) from healthy in vitro-grown potato plantlets were inoculated on Murashige and Skoog’s medium consisting of various levels of above mentioned drought stress-inducing agents. Data was recorded on 60th day of incubation exhibited a severe reduction in most of the growth parameters at 0.10 and 0.15 M of sorbitol and mannitol, respectively, and at 5–10% PEG. Similar results were observed when the sucrose level varied from 3% except for the number of roots and plant dry weight, which exhibited an increase in increasing the sucrose level. Data collected for total soluble protein content and activity of an antioxidant enzyme (superoxide dismutase) unveiled an overall increasing trend in osmotically stressed potato plants suggesting their major action in detoxification of active oxygen species produced under osmotic stress. Polyamines (putrescine, spermidine, and spermine) increased significantly in both the cultivars of potato by using osmotic stress-inducing agent in the present investigation indicating their positive role in stress alleviation. Overall results indicated that potato cultivar Desiree was more stress-tolerant than the cultivar Cardinal.