Effect of Molecular Species of Leaf Cerebroside to Thermal Reactions in Crops

1.研究了植物冷敏性与脑苷类成分的关系。采用反相高效液相色谱法从高等植物中分离出主要的脑苷类成分，并用差示扫描量热仪(DSC)分析了它们的热致行为。在8-不饱和度时，脑苷脂分子物种的相变温度随几何异构体的不同而发生显著变化。总体而言，顺式-8-不饱和异构体的相变温度低于反式-8-不饱和异构体。高等植物叶片脑苷脂的化学成分因品种和生长阶段的不同而变化不大。低温驯化使冷敏感植株的脑苷类成分变化不大，而耐冷植株的脑苷类成分发生了萝卜幼苗的变化和豌豆上胚轴的剧烈变化。冷驯化使耐冷萝卜幼苗和豌豆上胚轴的脑苷脂/甘油磷脂比值增加，而对冷敏感的南瓜和绿豆下胚轴的脑苷脂/甘油磷脂比值降低或略有变化。冷驯化使抗寒和耐冷植物的甘油磷脂中的甘油二酯分子略有不饱和。在抗寒性较强的萝卜幼苗中观察到含有不饱和羟基脂肪酸的脑苷脂分子种类，而在冷敏性植株中未检测到。在光生长条件下，冷驯化使膜脂组成发生了显著变化。冷驯化使冷敏绿豆下胚轴内质网标志酶(NADH-cyyC还原酶)活性和磷脂酸含量增加。

1. Relationsphip between chilling sensitivity of plants and composition of cerebrosides was studied. Major molecular species of cerebrosides was isolated from higher plants by reversed phase HPLC and thermotropic behavior of them was analyzed by DSC. Phase transition temperature of cerebroside molecular species varied markedly with the geometrical isomers at the 8-unsaturation. In general, the cis-8-unsaturated species revealed low phase transition temperatures than the trans-8-unsaturated isomers.2. The chemical composition of leaf cerebrosides from higher plants was not very varied by varieties or growth stages. The cold acclimation resulted in a little change of cerebrosides composition from the chilling-sensitive plants, whereas those from the chilling-resistant plants were in a change of radish seedings and in a hard change of pea epicotyls. The cold acclimation resulted in an increase of the ratio of cerebrosides to glycerophospholipids from the chilling-resistant radish seedlings and pea epicotyls, but in a decrease or in a slight change of those from the chilling-sensitive squash and mung bean hypacotyls. The cold acclimation resulted in a slight unsaturation of the diacylglycerol moieteis from glycerophospholipids of both the chilling-resistant and chilling-sensitive plants. The molecular species of cerebrosides containing DELTA^<15> cis- unsaturated hydroxy fatty acids were observed in the chilling-resistant radish seedlings, but in chilling sensitive plants they were not detected.3. Membrane lipid composition changed remarkably with cold acclimation under the light growth conditions. The cold acclimation resulted in the increase of endoplasmic reticulum marker enzyme (NADH-cyy C reductase) activities and phosphatidic acid from chilling-sensitive mung bean hypocotyls.