Drought induced leaf protein alterations in sensitive and tolerant wheat varieties

Abstract

Wheat plants with a fully developed first leaf were subjected to severe but recoverable water stress. Leaves from drought tolerant (Katya and Zlatitza) and drought sensitive (Sadovo and Miziya) varieties in control, drought and recovery conditions were used for the experiments. The physiological response of drought tolerant varieties did not differ from the one of drought sensitive varieties at early seedling stage under these conditions. A comparative study of the ultrathin sections by transmission electron microscopy from control and drought stressed plants revealed prominent changes in mitochondrion fine structures. The relative cell area occupied by mitochondria was reduced in the drought sensitive varieties. An increased quantity of abscisic acid (ABA) was detected in drought stressed wheat plants. The drought sensitive varieties (Miziya and Sadovo) possessed higher azocaseinolytic activity. An immunoblotting analysis was performed for some specificity detection of protein response under drought conditions of Rubisco, Rubisco activase (RA), Rubisco binding protein (RBP), dehydrins (DHN), some heat shock proteins (HSP) and ATP dependent calpain protease (Clp) proteins. The obtained results showed that the drought tolerant varieties Katya and Zlatitza had higher levels of these proteins, especially RBP and Clp proteases. Our attention was focused on the coordinated response of Rubisco, RA, RBP, DHNs, HSPs and Clp proteases in stress conditions, such as drought. The biochemical response diversity in susceptible and tolerant wheat varieties is discussed.