Salt-induced and Salt-suppressed Proteins in Tomato Leaves

Tomato ( Solanum lycopersicum cv. Money Maker) seedlings at the two-leaf stage were grown in one-half strength Hoagland solution supplemented with 50 m m NaCl for 4 days, with 100 m m NaCl for 4 days, with 150 m m NaCl for 4 days, and with a final concentration 200 m m NaCl for 2 days. Solutions were refreshed every 2 days for treated and untreated seedlings. Non-treated plants were grown in nonamended one-half strength Hoagland solution. Three biological replicates (BR) were included for treated and control experiments. At the end of treatments, the uppermost three newly expanded leaves from all 12 plants in each BR were collected and bulked to extract total protein. Proteomic analysis resulted in the identification of several salt-induced and salt-suppressed proteins. Salt-induced proteins were: vacuolar H + -ATPase A1 subunit isoform (1.6-fold), germin-like protein (1.5-fold), ferredoxin-NADP (+) reductase (1.2-fold), quinone oxidoreductase-like protein (4.4-fold), heat-shock protein (4.9-fold), and pyrophosphorylase (1.7-fold). Salt-suppressed proteins were: ATPase alpha subunit (−1.5-fold) and rubisco activase (−1.4-fold). Proteins identified in this study affect cellular activities for antioxidant, stress protection, carbon fixation, and carbohydrate partitioning in young tomato leaves under salt stress.