Salinity adversely affects plant growth and production. Oat is a moderately salt-tolerant crop and can contribute to improving saline soil. The physiological and molecular responses of the oat plant to long-term salinity were studied. After a 16-day salt treatment (150 mmol L-1NaCl in Hoagland's solution), photosynthetic rate, maximum photosystem II photochemical efficiency, and actual efficiency of photosystem II decreased. The activities of superoxide dismutase, peroxidase, and catalase significantly increased. We also investigated the protein profiles of oat leaves in response to salinity and detected 30 reproducible protein spots by two-dimensional gel electrophoresis that were differentially abundant. Specifically, one protein was up-regulated and 29 proteins were down-regulated compared with the control. These 29 proteins were identified using MALDI-TOF mass spectrometry, and 19 corresponding genes were further investigated by quantitative real-time PCR. These proteins were involved in four types of biological processes: photosynthesis, carbohydrate metabolism and energy, protein biosynthesis, and folding and detoxification. This study indicates that the lower levels of Calvin cycle-related proteins, 50S ribosomal protein L10 and adenosine-triphosphate regulation-related proteins, and the high levels of antioxidant enzymes play important roles in the response of oat to long-term salinity stress.
Keywords: Antioxidant enzymes; Oat; Photosynthesis; Proteomics; Salinity stress.