Study and comparison of leaf proteome in maize (Zea mays L.) under salt stress

Salinity is a major abiotic stress that limits the growth and productivity of plants in many parts of the world due to increased use of poor-quality water for irrigation and soil salinity. Plant adaptation or tolerance to salinity stress involves alteration in physiological processes and metabolic pathways and activating molecular or gene networks. In this study, 2DE technique was used to identify proteins responsive to salinity stress in maize. Two maize lines with different responses to salinity stress; R10 (tolerant) and S46 (sensitive) were selected. In the eight-leaf stage, salinity stress treatment of 8 dS/m was applied to plants for 20 days and then leaf proteins were extracted. Spots with more than a 1.5-fold increase or decrease in their expression were isolated and sequenced by mass spectrometry. Functional classification of protein spots per line after MS/MS revealed that the differentlly expressed proteins have different metabolic activities. In the tolerant line (R10), 5 spots including Pyruvate orthophosphate dikinase proteins, ATP synthase subunit beta, Germin-like protein, Chlorophyll a-b binding protein, Triosephosphate isomerase, and 40S ribosomal protein, respectively showed an increased expression level. Moreover, in the sensitive line (S46), one spot showed an increased expression level that related to Proteasome subunit beta proteins, and two spots including Chlorophyll a-b binding protein and Ribulose bisphosphate carboxylase small chain protein showed a decreased expression level. The proteins identified in this study and the possible related biochemical pathways provide new information on the response of maize lines (R10 and S46) to salinity stress.