Effects of Low Temperature on Fatty Acid Composition of Thylakoid Membranes and Lipid Peroxidation in Leaves of Rice Seedlings

A newly-developed super-high-yielding hybrid rice Liangyoupeijiu and a traditional hybrid rice Shanyou 63(as control) were used to study the effects of low night temperature on leaves,mainly by measuring their lipid peroxidation and fatty acid composition of thylakoid membranes with two treatment temperatures 10°C and 25℃.In Shanyou 63,chlorophyll content in rice leaves was decreased obviously with the duration at low temperature, whereas it did not decrease statistically in Liangyoupeijiu.For both of the two hybrids,the contents of 16:0 and 18:0 components at 10℃ were significantly decreased,but there were no marked changes when treated at 25℃,and the contents of both 16:0 and 18:0 components in Liangyoupeijiu were higher than those in Shanyou 63.The contents of 18:1,18:2 and 18:3 component were increased statistically in both of the two hybrids,but those treated at 25℃ increased smoothly.And the content of 18:3 component increased less than that of 18:2.The IUFA(index of unsaturated fatty acid) of fatty acid was increased in the two hybrids,being lower in Liangyoupeijiu than in Shanyou 63.MDA content of the two hybrids showed a similar changing pattern to O_2~(-·) content,but the MDA content in Liangyoupeijiu was not increased statistically.The results indicated that,Liangyoupeijiu may be not sensitive to low temperature,and it may have strong chilling-resistance at the seedling stage.Under the chilling conditions,there was a close relationship between IUFA and lipid peroxidation,and both of them were associated with cold adaptation in rice,which suggested that the IUFA may be an indicator of chilling-resistance.The changes in fatty acid composition and protection system on membranes were the key factor of cold adaptation,especially the latter.