Soluble sugars and membrane lipids in winter wheats (Triticum aestivum L) during cold acclimation

Abstract

Winter wheats differing in cold hardiness were analysed for soluble sugars and membrane lipids during a cold acclimation period of 30 days at + 2 °C, followed by a dehardening period of 4 days at 20 °C.The content of sugars soluble in 80 per cent ethanol doubled during the hardening period, from 78 to 142 mg g-1 dw. The most drastic change was found in raffinose. The content of sugars decreased rapidly during dehardening. Glucose, sucrose, raffinose and the total sugar content were all significantly correlated with cold hardiness. After 30 days of acclimation 84 per cent of the variation in cold hardiness could be explained by the total sugar content.The total amount of lipids decreased by about 25 per cent during cold acclimation. There was a small shift in the fatty acid composition to more unsaturated ones but the total amount of fatty acids was more or less constant. Neither the total amount of lipids nor the total amount of fatty acids was significantly correlated with cold hardiness. The separate lipid components were only slightly correlated with the cold hardiness index.Using multiple regression, higher correlations with cold hardiness were found for lipids and sugars together than for any single component. More than 75 per cent of the variation in cold hardiness could be explained by a combination of the amounts of linolenic acid, palmitic acid, sucrose and fructose already present at the beginning of the acclimation period.