Exogenous Application of Ascorbic Acid to Induce Tolerance Against Salt Stress in Common Bean Plants

Common beans have an important place in the world due to its high nutritional values in the human diet and with the largest cropping area among the legumes. Besides, they are named as quite sensitive to salt stress. Salinity is one of the utmost abiotic stress factors limiting agricultural production, which affects plant growth and development at different levels. Lately, exogenous applications of signalling and/or protective molecules to various parts of plants are used to combat salt stress before or at the time of stress. In this context, this research was conducted to assess the influence of foliar-applied ascorbic acid (AsA) on electrolyte leakage (EL), activity of antioxidative enzymes, total protein (TSP) content and protein profiles in the two common bean genotypes (salt-sensitive “Local Genotype” and salt-tolerant “Şeker Fasulye”) at early growth stage under salinity (0, 50, 100, 150 mM NaCl). The genotypes were exposed to salt stress from fully developed true leaf at the third nodes emerged stage for two weeks, meanwhile 3 mM AsA was foliar-applied every three days. Salt stress increased EL in both genotypes and exogenous AsA application decreased EL value especially in “Local Genotype”. Foliar-applied AsA generally reduced the adverse effects of NaCl on AsA content of both genotypes. Exogenous AsA application also increased the activities of catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) in the salt-stressed common bean plants and did not play a role in the TSP content. However, it has been determined that SDS-PAGE protein profiles represent adaptive mechanisms for dealing with excess salt in common bean genotypes. The results suggested that foliar-applied AsA was effective in reducing the adverse effects of salinity especially in relatively salt sensitive common bean genotype.