Proteomics analysis reveals multiple regulatory mechanisms in response to selenium in rice

Selenium (Se) shows both beneficial and toxic effects on plant growth. Rice (Oryza sativa L.) seedlings cultivated under lower concentrations of sodium selenite showed enhanced growth, whereas higher concentrations of sodium selenite repressed seedling growth. To acquire detailed regulatory mechanisms underlying these effects, a comparative proteomics study using 2-dimensional gel electrophoresis and MALDI-TOF/TOF MS was performed. By comparison of gel images between Se treatments and control, 66 and 97 differentially expressed proteins were identified in shoot and root, respectively under at least one of the Se treatment concentrations. Gene Ontology and Clustering analysis reveal primary metabolism, photosynthesis and redox homeostasis are the most highly affected biological processes by Se treatments. Lower Se treatments (2 and 6 mg/L sodium selenite) activated antioxidative system, enhanced photosynthesis and primary metabolism. However, higher Se treatment (10 mg/L sodium selenite) damaged photosynthesis apparatus, inhibited photosynthesis and primary metabolism. Protein ubiquitination and phosphorylation may also play important roles in Se response in rice. In conclusion, our study provided novel insights into Se response in rice at the proteome level, which are expected to be highly useful for dissecting the Se response pathways in higher plants and for producing Se enriched rice cultivars in the future.