Seedlings of Phaseolus vulgaris L. were grown hydroponically in 50 mM NaCl for 21 d after presoaking in 30 ppm abscisic acid (ABA) for 8 h to study the effect of ABA and salinity on lipid root plasma membrane (PM). Before salt treatment seedlings were grown in Hoagland solution for 10 days. ABA alleviated the salt induced reduction in growth parameters expressed as dry mass (DM) and relative growth rates (RGR) of both shoot and root. Pre-treatment with ABA increased the contents of benefit ions (Ca2+ and K+) and decreased those of toxic ones (Na+ and Cl-) which were altered under salt stress. A dangerous effect on the lipid root PM was observed with salt treatment as represented in altered total lipid, classes of phospholipids, unsaturated and saturated fatty acids and classes of sterols. Exogenous application by ABA mitigated the damage effect by salt on PM, increased total lipid, alleviated the alteration in phospholipid classes with the increase of phosphaidylcholine/ phosphatidylethanolamine (PC/ PE) ratio. ABA also increased unsaturated / saturated fatty acids and ameliorated the salt effect on sterol classes. Thus, it might be concluded that priming of seeds with ABA is promising for mitigating the damage effect of salinity expressed in the maintenance of PM and hence ion homeostasis and consequently seedling growth.
Key words: Exogenous Abscisic Acid, Salinity, Lipid Root Plasma Membrane, Phaseolus Vulgaris
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