Comparative proteomics of salt tolerance in Arabidopsis thaliana and Thellungiella halophila.

Salinity is a major abiotic stress affecting plant cultivation and productivity. Thellungiella halophila is a halophyte and has been used as a model for studying plant salt tolerance. Understanding the molecular mechanisms of salinity tolerance will facilitate the generation of salt tolerant crops. Here we report comparative leaf proteomics of Arabidopsis, a glycophyte, and its close relative Thellungiella, a halophyte, under different salt stress conditions. Proteins from control and NaCl treated Arabidopsis and Thellungiella leaf samples were extracted and separated by two-dimensional gel electrophoresis. A total of 88 protein spots from Arabidopsis gels and 37 protein spots from Thellungiella gels showed significant changes. Out of these spots, a total of 79 and 32 proteins were identified by mass spectrometry in Arabidopsis and Thellungiella, respectively. Most of the identified proteins were involved in photosynthesis, energy metabolism, and stress response in Arabidopsis and Thellungiella. As a complementary approach, isobaric tag for relative and absolute quantification (iTRAQ) LC-MS was used to identify crude microsomal proteins. A total of 31 and 32 differentially expressed proteins were identified in Arabidopsis and Thellungiella under salt treatment, respectively. Overall, there were more proteins changed in abundance in Arabidopsis than in Thellungiella. Distinct patterns of protein changes in the two species were observed. Collectively, this work represents the most extensive proteomic description of salinity responses of Arabidopsis and Thellungiella and has improved our knowledge of salt tolerance in glycophytes and halophytes.