Glycolysis Metabolic Mechanism Response Exogenous Salicylic Acid Under Low-temperature Of Winter Wheat

During growth and development,plants will face various stresses,including freeze stress.The accumulation of sugar and pyruvic acid can improve the viability for plants under low temperature,Including soluble reducing sugar,fructose and sucrose played a key role in plant cells osmotic.Salicylic acid(SA),as an important signal molecule,has a important role in the process of plant response to abiotic stress.In this work,1 mmol�L-1 exogenous SA was applied to leaf of the strong cold hardiness wheat cultivar DN1 and weak cold hardiness wheat JM22,and samplings including leaf and rhizome at the 5,0,-10,and-25�C in the field,we measured the content of soluble reducing sugar,sucrose,fructose and pyruvic acid,activities of key enzymes and gene expression levels of glycolysis metabolic pathway to reveal the exogenous SA how to improve the wheat seedling's cold resistance cope with cold stress,and helps to explain the winter wheat strong cold hardiness and its basic mechanism.The study also can provide the theory basis and certain theory for the application exogenous hormones to increasing winter wheat cold resistance.(1)Exogenous SA treatment promoted the accumulation of soluble reducing sugar,sucrose,fructose and pyruvic acid content in the two winter wheat leaves and rhizome,particularly in the rhizome.In the sub-zero temperatures,compared with JM22,DN1 accumulated more carbohydrates and the wheat can over-wintering the winter period safety.(2)After exogenous SA treatment,the activities of glycolysis metabolic pathways key enzymes(hexokinase?phosphofructokinase)improved significantly compared with the contro l in DN1 and JM22;but the activity of pyruvate kinase was reduced significantly in the J M22 below 0�C.This suggest that exogenous SA treatment can accumulated more intermed iate metabolite and enough energy though increasing the key enzymes activities of glycolys is metabolic to maintain the energy dissipation at the wintering period,particularly in the DN1.(3)Exogenous SA treatment increased the relative expression levels of TaHx K and TaPFK of glycolysis metabolic in the DN1 and JM22,particularly in the DN1;however the relative expression levels of TaPK was down-regulated in the JM22,but which was up-regulated in the DN1.This clarify that exogenous SA promoted glycolysis metabolic pathway of winter wheat in the physiology,also confirmed that the exogenous SA could increase the expression level of the key enzyme genes of the glycolase,and then improving the resistance of winter wheat to low temperature capacity.(4)Correction analysis showed that exogenous SA treatment improved the correlation of PFKactivity with the relative expression levels of TaHx K?TaPFK?TaPK in DN1 leaves and rhizome;The correlation of sucrose content with the activities of Hx K?PFK?PK showed significant positive correlation though exogenous SA treatment compared with control.From the above,after exogenous SA treatment,improved the glycolysis metabolic pathway by the activities of key enzymes and genes expression of glycolysis was increased in DN1,lead to accumulate more sugar and pyruvic acid,results to DN1 win a strong ability of cold resistance in freezing condition.