Salinity is one of the most severe environmental factors that may impair crop productivity. A proteomic study based on two-dimensional gel electrophoresis is performed in order to analyze the long-term salinity stress response of Thellungiella halophila, an Arabidopsis-related halophyte. Four-week-old seedlings are exposed to long-term salinity treatment. The total crude proteins are extracted from leaf blades, separated by 2-DE, stained with Coomassie Brilliant Blue, and differentially displayed spots are identified by MALDI-TOF MS or QTOF MS/MS. Among 900 protein spots reproducibly detected on each gel, 30 spots exhibit significant change and some of them are identified. The identified proteins include not only some previously characterized stress-responsive proteins such as TIR-NBS-LRR class disease resistance protein, ferritin-1, and pathogenesis-related protein 5, but also some proteins related to energy pathway, metabolism, RNA processing and protein degradation, as well as proteins with unknown functions. The possible functions of these proteins in salinity tolerance of T. halophila are discussed and it is suggested that the long-term salinity tolerance of T. halophila is achieved, at least partly, by enhancing defense system, adjusting energy and metabolic pathway and maintaining RNA structure.
GAO Fei ZHOU YiJun HUANG LingYun HE DaChengt ZHANG GenFa
High salinity stress is a major environmental factor that limits plant's distribution and productivity. An Arabidopsis-related halophyte,Thellungiella halophila,is an emerging model system used for plant abiotic stress tolerance research. Previous studies have suggested that protein phosphorylation has a crucial role in the high salinity response in plants. However,the phosphoproteome differential expression under high salinity stress in halophytes has not been well studied. In this report,phosphoproteome differential expression was analyzed under high salinity stress in Thellungiella roots. Twenty-six putative phosphoproteins were found to have changed expression pattern at the post-translational level. Twenty of these were identified by mass spectrometric analysis,including 18 upregulated and two downregulated phosphoproteins. These proteins were involved in a variety of cellular processes,such as signal transduction,ROS detoxification,energy pathway,protein synthesis and protein folding. While most of these salt-responsive putative phosphoproteins are known salt-stress-related proteins,some of them have not been previously reported. Our results provide not only new insights into salt stress responses in Thellungiella but also a good foundation for further investi-gation of these high salinity-regulated phosphoproteins.
