The beta subunit of glyceraldehyde 3-phosphate dehydrogenase is an important factor for maintaining photosynthesis and plant development under salt stress—Based on an integrative analysis of the structural, physiological and proteomic changes in chloroplasts in Thellungiella halophila

Abstract Thellungiella halophila , a new model halophyte, can survive under highly saline conditions. We performed comparative proteomics of chloroplasts from plants grown under different saline conditions. Seventy-five salt-responsive proteins were positively identified by mass spectrometry, which represented 43 unique ones. These proteins were categorized into 7 main pathways: light reaction, carbon fixation, energy metabolism, antenna proteins, cell structure, and protein degradation and folding. Saline conditions increased the abundance of proteins involved in photosynthesis, energy metabolism and cell structure. The results indicated that Thellungiella could withstand high salinity by maintaining normal or high photosynthetic capacity, reducing ROS production, as well as enhancing energy usage. Meanwhile, the ultrastructural and physiological data also agree with chloroplast proteomics results. Subsequently, the glyceraldehydes 3-phosphate dehydrogenase beta subunit (GAPB) involved in carbon fixation was selected and its role in salt tolerance was clarified by over-expressing it in Arabidopsis. ThGAPB-overexpressing plants had higher total chlorophyll contents, dry weights, water contents and survival rates than that of wild type plants. These results indicated that ThGAPB might improve plant salt tolerance by maintaining higher recycling rates of ADP and NADP + to decrease ROS production, helping to maintain photosynthetic efficiency and plant development under saline conditions.