The use of osmoregulators and antioxidants to mitigate the adverse impacts of salinity stress in diploid and tetraploid potato genotypes (Solanum spp.)

BACKGROUND: Many arid and semi-arid areas endure from extensive salinization of agricultural land. Nevertheless, it must either develop salinity-tolerant varieties or use agronomic treatments to alleviate the symptoms of stress. Although the cultivated potato, Solanum tuberosum L., is relatively salt sensitive, salinity tolerance was demonstrated in several Solanum relatives. Knowledge of genetic variation for salinity tolerance across diverse species is required for breeding of salinity-tolerant cultivars. Higher osmotic pressures associated with salinity impede plant development and cause plant death; yet, the exogenous application of cellularly recognized molecules to withstand such stress might be a key method. RESULTS: In vitro studies were performed to determine how much genetic variability for salinity tolerance exists in S. tuberosum (tbr), a tetraploid species and S. chacoense (chc), a diploid species in which 13 genotypes were evaluated under 100, 200 or 300 mmol L⁻¹ NaCl and the average tested parameters were compared with the control (no stress). A further experiment was conducted to investigate the effect of exogenous application of osmoregulators and antioxidants, namely, glycine betaine (GB), proline (P) and salicylic acid (SA) at 400, 200 and 100 mg L⁻¹, respectively, which applied solely to counteract the harmful effect of stress on potato plants. The results showed that when plants exposed to salinity, root characteristics, plantlet water content % (PWC), chlorophyll and K⁺ content, and callus formation all substantially reduced; however, Cl⁻ and Na⁺ levels, as well as catalase and peroxidase activity, were elevated. In general, chc showed more tolerance compared to tbr with genetic diversity within and among species. Under stress, chc clones, ‘A-6’, ‘C-8’ and ‘D-2’ and tbr cultivars, ‘Diamond’ and ‘Russet Burbank’ were more tolerant and yielded the greatest salinity tolerance index. Under stress but with applied GB, SA and P, the adverse consequences of stress were relieved. GB was found to be a good treatment for enhancing all the examined traits. CONCLUSION: The results indicated that there is a significant genetic variation in salt tolerance between (tbr) cultivars and (chc) clones. GB followed by SA and P could completely or partly reverse the adverse impact of salinity stress on potato plants.