Effect of low temperature stress on winter wheat membrane lipid composition and membrane permeability under exogenous abscisic acid treatment

Two winter wheat cultivars of Dongnongdongmai1(freezing- tolerant) and Jimai 22(freezing-sensitive) were used to investigate the effects of exogenous ABA on lipid composition under cold stress. Leaves were sprayed with 10-5mol· L-1ABA when seedings were at the 3-trure-leaf stage in the lowest temperature for 10 d at 4, 0,-10,-25℃ to study the effect of exogenous ABA on lipidcomposition. The results showed that the contents of unsaturated fatty acids gradually decresed in the two cultivars, and the IUFA of Dongnongdongmai 1 were lower than Jimai 22 in leaves. The linolenic acid contents of Dongnongdongmai 1 was higher and the palmitic acid contents was lower that those of Jimai 22, C(16:1) and C(18:3) were determined as the reference for freezing rolerant indicators. The treatment under exogenous ABA have highter unsaturated fatty acids contents than the treatment of water.especially in maxmum temperature of 4℃,-25℃ in leaves and nods.The unsaturated fatty acids gradually incresed on the nods of Dongnongdongmai 1, and the IUFA was higher than Jimai 22, achieved very significant levels. The contents of MDA and ralative electrical conductivity gradually decresed in the two cultivars, and the decreased in Dongnongdongmai 1 were lower than Jimai 22, and achieved significant levels. These showed that ABA improving cold hardiness of freezing-tolerant culrivar than freezing-sensitive cultivar.