ATP-dependent proteolysis contributes to the acclimation-induced drought resistance in spring wheat

The effect of water deficit on the ATP-dependent proteolysis and total protein degradation was estimated in the leaves of spring wheat (Triticum aestivum L.) acclimated and non-acclimated to drought. The rate of ATP-dependent proteolysis, quantified as a difference between degradation of 125I-lysozyme under ATP-regenerating and ATP-depleting systems, accounted for about 55 % of total 125I-lysozyme degradation in fully turgid wheat leaves. In the non-acclimated leaves dehydration decreased sharply ATP-dependent proteolysis catalyzed by proteasome down to about 5% while in the leaves acclimated to drought water deficit raised ATP-dependent proteolysis to 87 % of total 125I-lysozyme hydrolysis.