Physiological and proteomic mechanisms of waterlogging priming improves tolerance to waterlogging stress in wheat (Triticum aestivum L.)

• Waterlogging priming (WP) enhanced tolerance to waterlogging stress in wheat.
• WP plants showed higher antioxidant capacity in the ascorbate–glutathione cycle.
• Proteins related to ethylene biosynthesis showed higher expression in WP plants.
• Exogenous ethylene increased plant tolerance to waterlogging stress in wheat.

Both physiological and proteomic analyses were performed to explore the mechanism of waterlogging priming on plant tolerance to waterlogging stress in wheat. Compared with non-primed plants (CW), waterlogging primed plants (WW) showed higher activity of enzymes in the ascorbate–glutathione cycle. In agreement with the physiological results, proteins associated with energy metabolism and stress defense had a significantly higher expression in WW than CW. In particular, the proteins related to ethylene biosynthesis showed a higher expression in WW than CW. Moreover, exogenous ethephon (EW), ethylene precursor 1-aminocyclopropanecarboxylic acid (ACW) and an ethylene inhibitor amino-oxyacetic acid were applied before waterlogging to ascertain the effects of ethylene on waterlogging. Use of ACW resulted in a higher yield as compared with non-pretreatment with waterlogging stress. A greater yield loss in EW was due to the fact that higher ethylene concentration led to a more severe seed abortion. Use of ethylene alleviated the negative effects on leaf photosynthesis by increasing stomatal conductance under waterlogging stress. In short, priming alleviated the negative effects of waterlogging stress in wheat, and use of exogenous ethylene resulted in an increase in leaf photosynthesis by promoting stomata opening under waterlogging stress.