Effects Of Salicylic Acid Or Heat Acclimation On The Peroxidation Of Membrane-lipid Of Leaves In Grape Seeldings

Salicylic acid (SA) is a phytohormone with ubiquitous distribution among plants. It was shown to regulate a large variety of physiological processes in plant. The results showed that heat acclimation or SA could induce thermotolerance of plant.One-year-old grape plants (Vitis Vinifera L.cv. Cabernet Sauvignon) were used as experiment materials. After they were treated by heat acclimation(38℃) and salicylic acid(SA) with concentration of 100μmol.L-1 in different times, respectively, the effects of SA and heat acclimation on the peroxidation of membrane-lipid of leaves in young grape plants were studied. The physiology and biochemical mechanical mechanism of inducing thermotolerance of plants on heat acclimation and with concentration salicylic acid were discussed. All above provided the base theory for salicylic acid. The following results were obtained:SA treatment and heat acclimation could weaken the Peroxidation of Membrane-lipid of Leaves in young grape plants. The contents of MDA in leaves decreased significantly after heat acclimation and SA treatment 1 hour, and then, the content of MDA increased, but the content of MDA were more than the control during the 12 hours after they were treated . SA treatment and heat acclimation could decreased significantly PRPP in leaves of grape. The content of O₂^- decreased rapidly after heat acclimation and SA treatment 1 hour, and reached a peak values after treated 12 hour, and then, the content of O₂^- increased ,but the content of MDA were less than the control after they were treated 24 hours. The content of hydrogen peroxide(H₂O₂) in grape leaves were drastically elevated at1h,then rapidly declined.SA treatment and heat acclimation could decrease the activity of lipidoxidase(LOX) Activities of antioxidant enzymes including superoxide dismutase(SOD),peroxidase(POD) were elevated. Heat stress could cause the increase of the content of salicylic acid in leaves. The contents of free SA and conjugated SA in leaves reached a peak values after heat stress 1 hour, and then, the content of SA decreased rapidly, especially free SA in leaves performed more active than conjugated.These results indicated that SA treatment and heat acclimation showed common mechanism of inducing thermotolerance of plants.