Study Of Exogenous Salicylic Acid On Physiological Characteristics And The Nature Of Protein Kinase Of Grape Young Plants Under High Temperature Stress

This trail was in order to define the influence of the exogenous SA on grape seedlings heat resistanceand membrane lipid peroxidation under high temperature stress(HTS) and the influence of(ascorbateglutathione, As A-GSH) circulation metabolism, find out the influence of different substrates, differentprocessing time, different concentration of different metal ions and different concentration of ATP onprotein kinase activity, certain the types of protein kinase induced by high temperature and exogenoussalicylic acid. In this trail, two-year-old vitis vinifera L. Crinson seedless grape young plants were chosento explore the effects of exogenous SA on HTS by studying the physiological characteristics and thecharacter of protein kinase induced by HTS and exogenous SA. Got the following results:1.The contents of malondialdehyde(MDA) and electrolyte permeability of grape leaves increased withthe extension of time under HTS, the augmenter of contents of MDA and the electrolyte permeability canbe increased by spraying exogenous SA on grapes under HTS, especially HTS for more than 60 min, theaugmenter of MDA contents and electrolyte permeability could be significantly increased by exogenous SA,thus effectively protecting the integrity of the cell membrane; It could maintain higher activity ofsuperoxidase(SOD), peroxidase(POD), catalase(CAT) by spraying exogenous SA under HTS, and longerduration of stress(> 120 min) can significantly improve the augmenter of activity of SOD, POD, CAT,enhances the ability of removing active oxygen and free radicals in cells; the content of hydrogen peroxideand superoxide anion producing rate of grape leaves increased with the extension of time. It wassignificantly reduced by spraying exogenous SA on the grape leaves under high temperature, so the level ofmembrane lipid peroxidation was reduced, the heat resistance of grape seedlings was increased.2.The contents of free proline in grape leaves increased with the extension of time under HTS, thecontent of soluble protein with the extension of stress time appears to increase the change trend of lower,after 60 min in stress when the content of soluble protein increased to the maximum. High temperaturestress and exogenous salicylic acid can induce stimulus the activity of protein kinase of grape leaves, theactivity of protein kinase increased at first,then decreased with the stress change trend, and the change ofprotein kinase activity and soluble protein content changes with high consistency, namely stress 60 minsoluble protein content increased to the maximum, protein kinase activity has increased to the maximum atthe same time.3. The synthesis of ascorbate(As A) speed was inhibited at the beginning under high temperature,thecontents of As A in grape leaves was declined under HTS. That might be due to adaptability to hightemperature reaction of grape leaves, the As A contents increased later. the stress time over 120 min,theAs A contents decreased significantly. The possible reason was that long time high temperature sharplychanged the active oxygen metabolism imbalance, produced a large number of free radicals, As A asantioxidants in the quenching free radicals, so its content was lower. With the increase of prolonged stress,exogenous SA could induce accumulation of glutathione(GSH) content, reduce the content of oxidativeglutathione(GSSG). Spraying under high temperature stress with 150 μmol/L SA could promote As A andGSH in the circulatory system of As A and GSH content accumulation, and exogenous SA could maintainhigher As A and GSH in the circulatory system ascorbic acid peroxidase(APX), dehydroascorbate reductase(DHAR), monodehydroascorbate reductase(MDHAR), glutathione reductase(GR) activity, reduced theHTS for a long time(> 240 min) dehydrogenation under the contents of ascorbic acid(DHA), promoted therapid effective operation of As A and GSH cycle, reduce the oxidative damage of plants, alleviated injury ofgrape seedlings under high temperature.4.The high temperature and exogenous SA could induce a kind of protein kinase that could exist in themyelin basic protein(MBP) as substrates, promoted protein kinase protein phosphorylation reaction;established experimental conditions to protein phosphorylation under HTS and exogenous SA treatment,heat treatment, and cross processing of protein phosphorylation reaction experiment system wasphosphorylated substrates with MBP, reaction time was best for 10 min; ATP suitable concentration was50μmol/L. The Mg2+ for activation pretreatment and HTS induced protein kinase activity played animportant role, and the concentration was not the higher the better. But the appropriate concentration needsto be qualified in a certain range, protein kinase activity declined with Mg2+ concentration was too high, thebest concentration of Mg2+ tendency at 5.0mmol/ L was advisable.5.Using the biochemical method, we explored the nature of the protein kinase induced by HTS andexogenous SA by using the single substrate MBP, protein kinase inhibitors W7 and PD98059, specificity ofprotein phosphatase YOP and its inhibitor Na3VO4. And it preliminarily deduced that a kind of proteinkinase could be induced by exogenous SA treatment under HTS; phosphorylation reaction took MBP as thesubstrate, and both the induction of MAPK kinase were homogeneous type.