Amelioration of NaCl-induced Alterations on the Plasma Membrane of Allium Cepa L. by Ascorbic Acid

The influence of exogenous ascorbic acid (0.5 mM) in counteracting NaCl-induced cellular alteration of onion bulb inner epidermis was investigated. Plasma membrane permeability, protoplasm swelling and cell viability were measured under the effect of 150 mM NaCl in presence and absence of ascorbic acid. Ascorbic acid was added simultaneously with salt or before salt treatment. Salt stress at 150 mM NaCl increased PM permeability to urea, the numbers of swollen protoplasm and cell mortality. Ascorbic acid protected NaCl-induced PM alterations and hence maintain its permeability and cell viability. The protective effect of ascorbic acid was more pronounced when added simultaneously with NaCl. The mitigative effect of AA might be via direct interaction with PM components and/or inhibition of lipid peroxidation induced by AOS formed under salinity. It is possible that ascorbic acid counteract the deleterious effect of NaCl on the cell membrane which may lead to increased salt tolerance in plants.