Sugar Beet M14 Under Salt Stress Strain Of Comparative Proteomics Analysis

Salt stress is one of the major abiotic stresses affecting plant growth, development,and productivity of crops all over the world. More than6%of land throughout the worldis salt-affected. How to improve plant salt stress tolerance and make good use of thesalinity soil has become a focus of plant biology research.Sugar beet is a dicotyledonous plant of the Chenopodiaceae that has a high economicvalue. It is a crop of halophytic nature and can survive high salt conditions, thus is anexcellent material for studying plant response and tolerance to salt stress. Sugar beetmonosomic addition line M14was obtained from the intercross between Beta vulgaris L.and Beta corolliflora Zoss., and it contains the Beta vulgaris L. genome with the additionof chromosome9of Beta corolliflora Zoss. B. corolliflora has many characteristicsincluding apomixes and tolerance to drought, cold and salt. The M14has retained someof these characteristics, e.g., stress tolerance and apomixis.In this study, we reported proteomic analysis of M14leaves and roots under500mM NaCl treatment for seven days. Proteins were extracted from leaves and roots ofcontrol and salt-treated plants, quantified and separated using two-dimensionaldifference gel electrophoresis (2D-DIGE). In leaves, a total of40protein spots showedsignificant changes in salt-stressed samples compared to control samples. A total of21protein spots were increased in levels and19protein spots were decreased. In roots, atotal of36protein spots showed significant changes in salt-stressed samples compared tocontrol samples, with24spots increased and12spots decreased in abundance.The differentially expressed protein spots were excised, in-gel trypsin digested andanalyzed using tandem MS. All except one of the differentially expressed proteins spotswere successfully identified. The identified protein spots corresponded to38uniqueproteins in leaves and29in roots. The identified proteins cover a wide range ofmolecular functions, including metabolism, protein folding, photosynthesis, protein degradation, energy, signaling, protein synthesis, membrane and transport, transcriptionrelated, cellular structure, stress response and defense. In leaves, the salt-responsiveproteins were classified into10categories, and in roots the proteins were grouped into11categories. In leaves, the largest group is the photosynthesis (24%) and metabolism(24%), followed by protein folding (18%). In roots, metabolism (30%) formed the largestgroup, followed by protein folding (22%) and protein degradation (11%). These findingsindicate that proteins involved in photosynthesis, metabolism, and protein folding play animportant role in salt-stressed leaves and proteins involved in metabolism, proteinfolding, and degradation are important in salt-stressed roots.Here SSH results were compared to the proteins identified by proteomics. Oneprotein up-regulated in leaves, S-adenosyl-L-methionine synthetase, showed significantmatch. These results suggest that leaves and roots can perceive salt stress and transmitthem to regulate transcription, protein synthesis and processing, thereby affecting thelevels of functional proteins in metabolism, protein folding, photosynthesis, proteindegradation etc. These processes work cooperatively to achieve homeostasis under saltstress conditions. This research has set the stage for further understanding of the salttolerance mechanisms in sugar beet.