Responses of Enzymatic Antioxidants of Potato Species under Osmotic Stress In vitro

To develop reproducible parameters for identification of drought tolerance of potato wild species or cultivars, response of tree wild species of potato Solanum bulbocastanum (intolerant), S. stoliniferum (semi- tolerant), S. acaule (tolerant) and a cultivar (S. tuberosum cv. ‘Agria’) (tolerant) to osmotic stress, using polyethylene glycol (PEG 15%) was studied using MS medium in vitro. Osmotic stress reduced shoot dry weight (SDW) and increased malondialdehyde, other aldehydes, ion leakage, hydrogen peroxides and the activity of lipoxygenases, superoxide dismutase, and catalase. Ascorbate peroxidase, glutathione reductase and guiacol peroxidase enzymes in potato species. However, the response of species was different to osmotic stress, such as accule showed the highest and bulbocastanum the lowest level of tolerance, in terms of SDW production. Correlation showed that ion leakage (r=-0.91**), catalase (r=-0.89**), malondialdehyde (r=-0.8**) and lypoxygeneses (r= 0.75**) were significantly correlated which may be used to screen potato genotypes to osmotic stress. The use of ion leakage parameter is recommended due to its low cast, precision and applicability.