This investigation was carried out to study the effect of water deficit stress on leaf proteome pattern and agronomic and physiological characteristics of two spring bread wheat varieties (Arg and Moghan3) with contrasting responses to drought stress. For this purpose, an experiment was conducted as a 2 × 2 factorial arranged as the randomized complete block design with five replications in a greenhouse of University of Tabriz, Iran. The factors consisted of two Arg and Moghan3 varieties and irrigation conditions (normal condition and drought stress, where water was withheld at the pollination stage). Based on the analysis of variance, significant differences were observed between two wheat varieties with respect to all studied characters except leaf chlorophyll content. Drought stress increased leaf temperature and reduced other characters. Leaf proteome analysis was performed by two-dimensional electrophoresis for both wheat varieties at two irrigation conditions. After quantification of spots with PDQuest software, 274 and 202 repeatable protein spots were identified in Arg and Moghan3 varieties, respectively. Among them, based on the induction factor and t-test, 73 and 64 protein spots showed significant changes in abundance in Arg and Moghan3 varieties, respectively. Out of 73 spots identified in Arg, 46 showed an increased expression and 27 showed a decreased expression. In Moghan3, out of 64 protein spots, 18 and 46 protein spots were up- and down-regulated, respectively. Moreover, 15 common protein spots in Arg and Moghan3 with significant changes in expression between normal and drought stress conditions were identified by applying MALDI-TOF/TOF mass spectrometry. Identified proteins were assigned to seven functional categories: photosynthesis, stress, defense and detoxification, glycolysis, transport, protein synthesis and transcription regulation. In general, proteins related to photosynthesis, stress, and defense and detoxification showed major changes which may be considered as important proteins contributing to drought tolerance of Arg in this study.
