ABA pretreatment can limit salinity-induced proteome changes in growing barley sprouts

A proteomic study was conducted on caryopses of barley cv. Stratus (Hordeum vulgare). The caryopses were germinated in darkness at 20 °C, according to one of the three experimental setups: (a) in distilled water for 24 h, followed by 100 mM NaCl for another 24 h (salinity stress, SS); (b) in 100 µM abscisic acid for 24 h, with rinsing in distilled water to remove residual ABA, followed by 100 mM NaCl for another 24 h (pretreatment with ABA + salinity stress, ABAS); and (c) only in distilled water, for comparison with the tested samples (control, C). After 48 h, proteomes were extracted from barley sprouts in each treatment, according to the method by Gallardo et al. (2002a, b, modified). Proteins were then separated by 2DE and analyzed by MALDI–TOF/MS (Bruker). Under salinity stress, we observed changes in the pattern of proteins involved in: (a) energy metabolism, (b) one-carbon metabolism, (c) cell wall biogenesis, lignification, and adhesion, (d) response to oxidative stress, desiccation stress, and other defense responses, (e) structure and organization of the cytoskeleton, (f) signal transduction, transcription and translation processing, and (g) protein turnover. Our results revealed that ABA can alter the response of barley seedlings to salinity stress. In general, ABA pretreatment limited stress-induced proteomic changes. Alterations in energy and one-carbon metabolism indicate the importance of ABA in glycolytic/gluconeogenic pathways and the SMM cycle during salinity stress. Other observations demonstrated the role of ABA in hemicellulose, cellulose and lignin biosynthesis, ROS scavenging, actin CK formation, control of PI signaling, chromatin-mediated mechanism of stress tolerance, mRNA stability, and protection against dehydration.