Proteomics reveals the effects of gibberellic acid (GA3) on salt-stressed rice (Oryza sativa L.) shoots

Salt decreases gibberellic acid (GA3) content in rice. Nevertheless, GA3 may exert a beneficial effect on salt-stressed rice. In our analysis, GA3 reduced NaCl-induced growth inhibition in rice (Oryza sativa L. cv. Nipponbare) in a concentration-dependent manner, including the length of root tissue. However, remains unclear. We employed a comparative proteomic analysis to elucidate the mechanism of GA3 activity in this phenomenon. 5-Day-old seedlings treated with salt and gibberellic acid (H2O, 0.5% NaCl, 0.5% NaCl + 100 μM GA3, and 100 μM GA3) for 48 h were used for the proteomics analysis. Eleven proteins differently regulated by salt and GA3 were revealed by 2D PAGE and were identified by MALDI-TOF MS. These proteins were identified as glutamyl-tRNA reductase, enolase, salt stress-induced protein (SALT protein), Os09g0249700, hypothetical protein OsJ_014066, putative chaperonin 21 precursor, Os04g0659300, hypothetical protein OsJ_025258, ribulose bisphosphate carboxylase, isoflavone reductase-like protein and phosphoglucomutase. Some of these proteins are involved in biochemical pathways such as photosynthesis and glycolysis, but others were found to be novel proteins involved specifically in the response to salt in rice. GA3 had a significant influence on the abundance of some salt-regulated proteins. Our studies have provided new insight to reveal the modulating effect of GA3 on salt stress in rice.