Proteomic Analysis On Salicylic Acid Enhances Wheat Seeding Drought Tolerances And Its Relationship With Ascorbate And Glutathione Cycle

Salicylic acid (SA), a key signaling molecule in higher plants, has beenfound to play a role in the response to a diverse range of phytopathogens and isessential for the establishment of both local and systemic-acquired resistance. Recentstudies have indicated that SA also plays an important role in abiotic stress-inducedsignaling, and studies on SA-modulated abiotic tolerance have mainly focused on theantioxidant capacity of plants by altering the activity of anti-oxidative enzymes.However, little information is available about the molecular mechanisms ofSA-induced abiotic stress tolerance.In the present study, we analysis the proteomic mechanisms of SA-inducedabiotic stress tolerance and the transcript levels of ASA-GSH biosynthesis relatedgenes.The main results of this study are as follows:a) Compared to the control, drought stress for3d dramatically reduced wheatseedling growth。However, in the presence of exogenous SA, the effect of droughtstress on wheat seedling growth was significantly abrogated. This was demonstratedby the significantly increased plant heights, fresh and dry weights. These resultsshowed that SA improved the growth of wheat seedlings under drought stressconditions. Accumulation of MDA in drought-stressed seedlings of wheat wassignificantly higher than compared to the control. In the presence of SA (SA+drought treatment), MDA concentrations were significantly reduced. This resultdemonstrated that the rate of lipid peroxidation under drought stress was counteractedby SA treatment in wheat seedlings.b) Eighty-two stress-responsive protein spots showed significant changes, which76were successfully identified by MALDI-TOF-TOF. Analysis of protein expressionpatterns revealed that proteins associated with signal transduction, stress defense,photosynthesis, carbohydrate metabolism, protein metabolism, energy production,could by involved in SA-induced growth and drought tolerance in wheat seedlings.Furthermore, the SA-responsive protein interaction network revealed35key proteins, suggesting that these proteins are critical for SA-induced tolerance.c) We isolated the full-length cDNA sequences of the glutathione-S-transferase1(GST1) and2(GST2) genes and measured the transcript levels of eight ASA-GSHbiosynthesis-related genes from wheat plants under stress. Exogenous SAsignificantly enhanced the transcript levels of the GST1, GST2, GR (glutathionereductase), and MDHAR (monodehydroascorbate reductase) genes during almost theentire drought period, but only increased those of DHAR (dehydroascorbate reductase)at12h, GPX1(glutathione peroxidase) at48h, GPX2(phospholipid hydroperoxideglutathione peroxidase) at12and24h, and GSHS (glutathione synthetase) at12,24and48h. This implies that SA alleviates the detrimental effects of drought stress onwheat seedling growth by influencing the transcript levels of ASA-GSHbiosynthesis-related genes.