Proteomic analysis of salt-stressed tomato (Solanum lycopersicum) seedlings: effect of genotype and exogenous application of glycinebetaine.

An investigation aimed at a better understanding of the molecular adaptation mechanisms of salt stress was carried out in 7-d-old tomato Solanum lycopersicum (L.) Mill cultivars Patio and 'F144', using a proteomic approach. Total proteins were extracted from radicles and hypocotyls collected from both non-saline control and salt-stressed seedlings, and separated by two-dimensional gel electrophoresis. Liqud chromatography-electron spray ionization tandem mass spectrometry (LC-ESI-MS/MS) identified 23 salt stress response proteins, classified into six functional categories. The effect of exogenously applied glycinebetaine (GB) on the salt stress-induced inhibition of growth in tomato seedlings of cultivars Patio and 'F144' and on the protein profile was investigated. It was found that GB could alleviate the inhibition of tomato growth induced by salt stress through changing the expression abundance of six proteins in Patio and two proteins in 'F144' more than twice compared with salt-stressed seedlings. Furthermore, the interaction analysis based on computational bioinformatics reveals major regulating networks: photosystem II (PSII), Rubisco, and superoxide dismutase (SOD). The results suggest that it is likely that improvement of salt tolerance in tomato might be achieved through the application of exogenous compatible solutes, such as GB. Moreover, quantitative and qualitative analysis of the differentially expressed proteins of tomato under salt stress is an important step towards further elucidation of mechanisms of salt stress resistance.