Integrated proteome analyses of wheat glume and awn reveal central drought response proteins under water deficit conditions.

MAIN CONCLUSION: Integrated proteome analyses revealed differentially accumulated proteins in the non-leaf green organs in wheat glume and awn that play important roles in photosynthesis and drought resistance. Two non-leaf green organs in wheat, glume and awn, have photosynthetic potential, contribute to grain yield, and also play roles in resistance to adverse conditions. We performed the first integrated proteome analysis of wheat glume and awn in response to water deficit. Water deficit caused a significant decrease in important agronomic traits and grain yield. A total of 120 and 77 differentially accumulated protein (DAP) spots, representing 100 and 67 unique proteins responsive to water deficit, were identified by two-dimensional difference gel electrophoresis (2D-DIGE) in glumes and awns, respectively, of the elite Chinese bread wheat cultivar Zhongmai 175. The DAPs of both organs showed similar functional classification and proportion and were mainly involved in photosynthesis, detoxification/defense, carbon/energy metabolism, and proteometabolism. Comparative proteome analyses revealed many more drought-responsive DAP spots in glumes than in awns, which indicate that glumes underwent more proteome changes in response to water deficit. The main DAPs involved in photosynthesis and carbon metabolism were significantly downregulated, whereas those related to detoxification/defense and energy metabolism were markedly upregulated under water deficit. The potential functions of the identified DAPs revealed an intricate interaction network that responds synergistically to drought stress during grain development. Our results from the proteome perspective illustrate the potential roles of wheat non-leaf green organs glume and awn in photosynthetic and defensive responses under drought stress.