Interactive Effects of PEG-induced Water Stress and CaCl2 on the Status of Calcium and Ca2+ Binding Proteins During Seedling Growth of Peanut (Arachis hypogaea L.) Cultivars

Abstract

Seedlings of two peanut cultivars (TPT-l and TPT-4) grown in distilled water for 12 d were subjected to polyethylene glycal (PEG-6000) induced water stress. Twenty mM CaCl z was added to the stressed seedlings to examine the ameliorative effect of PEG induced water stress. The seedlings were analysed for calcium content at 2-d intervals for 7 d. Calcium-binding proteins (CaBPs) were quantified in the seedlings of different treatments in the two cultivars. Water stressed seedlings had significantly lower calcium content. The seedlings of the two cultivars showed differences in the accumulation of calcium under treatments. CaBPs fractionated through DEAE cellulose columns. The pooled fractions of the proteins separated by SDS-PAGE contained different molecular weights of polypeptides. The polypeptides were resolved on the CaClz-treated seedlings better than either control or water stressed and PEG + CaCl z treated seedlings. Calmodulin isolated from the seedlings of both the cultivars showed a single band co-migrating with 15 kDa protein of Bovine brain calmodulin. Differences between the cultivars, treatments and interaction for the parameters were significant. The two cultivars showed differences in calcium-binding proteins under PEGinduced water stress and its alleviation by CaCl z in peanut seedlings.