低温对水稻剑叶膜脂过氧化和脂肪酸组分的影响

以高产杂交稻两优培九和常规杂交稻汕优63为材料，研究夜间低温对剑叶叶绿素、类胡萝卜素、类囊体膜脂过氧化和脂肪酸组分的影响。结果表明，两个品种叶绿素和类胡萝卜素含量及叶绿素a/b随着处理时间延长和温度降低而下降，而类胡萝卜素含量与叶绿素总量的比值上升。低温处理4 d后，两个品种MDA含量均明显高于对照，同时也比处理2 d时高。超氧阴离子含量随着处理温度的降低、时间的延长而上升。两个品种的SOD活性在处理4 d后都下降。两优培九的CAT活性平缓下降，而汕优63则显著下降。脂肪酸的不饱和度随着处理温度的降低和时间的延长逐渐上升，汕优63上升幅度较大，推测其对低温更为敏感。夜间低温引起剑叶类囊体膜脂过氧化加剧，脂肪酸不饱和度上升，这两方面的变化有着密切的关系，且都与杂交稻的冷适应性相关。

Effects of Low Temperature on Lipid Peroxidation and Fatty Acid Composition of Flag Leaf in Rice(Oryza sativa L.)

A newly-developed super-high-yielding rice(Oryza sativa L.) cultivar Liangyoupeijiu and a traditional cultivar Shanyou63 (as control) were used to study the effect of low temperature at night on flag leaves by mainly measuring their carotenoids content, lipid peroxidation and fatty acid composition of thylakoid membranes. 20℃ and 15℃ were the two treatment temperatures. The results showed that, for both of the two cultivars, chlorophyll content of 20℃ treatment group was decreased statistically compared with that of field-grown plants, but that of 15℃ treatment group was not decreased significantly. Carotenoids content and chlorophyll a/b ratio were decreased in both cultivars with longer treatment time and lower temperature, but the ratio of carotenoids content to chlorophyll content was increased. With 4 d low temperature treatment, MDA content of the two cultivars was significantly higher than that of field-grown plants, also higher than that with two day’s treatment. O₂^．- content was also increased with the treatment of longer time and lower temperature. The activity of SOD for both cultivars was declined after 4 d low-temperature treatment. The activity of CAT was declined less in Liangyoupeijiu than in Shanyou 63. The main fatty acids in thylakoid membrane of the two cultivars were palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid. And the contents of palmitic acid and linolenic acid were higher than other three. The IUFA (index of unsaturated fatty acid) of fatty acids showed a similar changing pattern to that of O₂^．- content in Liangyoupeijiu, but that was greatly increased in Shanyou 63, which might be more sensitive to low temperature. In the chilling conditions, there was a close relationship between the increase of IUFA and the addition of lipid peroxidation, and both of them were relative to the cold adaptation in rice. The IUFA may be an indicator of chilling-resistant. The changes of fatty acid composition and protection system on membranes may be the key factor of cold adaptation, especially the latter, and the ultimate objective is to alleviate the yield decrease under low temperature.