Metabolic and molecular basis for the salt and alkali responses of Suaeda corniculata

High salinity and alkalinity, two of the most widespread abiotic stressors which largely impact plant growth and development. Most researches focus on how plant cope with neutral salt stress, the underlying mechanism of plant response to alkali stress has not been systematically studied, and little information is available as reference. The halophyte Suaeda corniculata is an outstanding pasture with strong tolerance to salt and alkali stress. Here, the combined analysis of H-1 NMR-based metabolomics, 2DE-based proteomics and physiological observation were performed, to demonstrate the comparison on metabolic and molecular network of S. corniculata responsive to salt and alkali stress. Our results showed that the alkali stress induced more severe effect on the plant growth than salt stress. The metabolomic and proteomic characteristics showed distinct regulation patterns in response to salt and alkali in S. corniculata. The evaluation of reactive oxygen species (ROS)-scavenging systems, as well as abundance patterns of salt and alkali-responsive proteins or metabolites indicated that the hyper activation of ROS scavenging system, including APX dependent AsA-GSH cycle and Prx/Trx pathway, played a major role in maintaining redox homeostasis to alleviate oxidative damage. In addition, the accumulation of glycine betaine mainly contributes to the re-establishment of osmotic homeostasis. Importantly, the high abundance of germinlike proteins and enzymes involved in fatty acid metabolism might positively contribute to the alkali tolerance of S. corniculata. Together, this study provides novel insights into the physiological and metabolic features in halophyte S. corniculata to salt and alkali stress, and this deepens our understanding of how halophytes reprogram the molecular activities to cope with salinity and alkalinity in soil.