镉胁迫对平邑甜茶脂肪酸构成及脂质过氧化的影响

以平邑甜茶幼苗为试材，研究了镉胁迫下幼苗叶片和根系膜脂肪酸构成、活性氧、脂氧合酶和丙二醛含量的变化.结果表明：氯化镉处理后7～12 h，脂肪酸种类及其相对含量变化最为明显.处理后7 h，叶片和根系脂肪酸不饱和水平升至最高，含量分别达8282%和7243%；叶片可检测到的脂肪酸在处理后12 h由11种增至14种，根系则在处理17 h后由4种增至6种.O₂^.-产生速率在处理3 h、H₂O₂含量在处理7 h时升至最高，丙二醛含量和脂氧合酶活性则随着处理时间的延长逐渐增加.镉胁迫通过诱导活性氧和脂氧合酶来改变平邑甜茶脂肪酸构成，并引起脂质过氧化；镉处理12 h前，脂质过氧化是活性氧和脂氧合酶的共同结果；但处理12 h后，脂质过氧化加剧主要在于脂氧合酶活性的持续增加.

Effects of cadmium stress on fatty acid composition and lipid peroxidation of Malus hupehensis

This paper studied the fatty acid composition, reactive oxygen species (ROS), lipoxygenase (LOX) activity, and malondialdehyde (MDA) content in the leaves and roots of Malus hupehensis seedlings under effects of cadmium (Cd) stress. Noticeable changes were observed in the kinds and relative contents of fatty acids after treated with CdCl2 for 7〖KG-*2〗-〖KG-*7〗12 hours. The relative contents of unsaturated fatty acids in leaves and roots reached the maximum after treated for 7 hours, being 8282% and 7243%, respectively. The kinds of fatty acids in leaves increased from 11 to 14 after treated for 12 hours, while those in roots increased from 4 to 6 after treated for 17 hours. The O2〖SX（B-*3〗-〖〗·〖SX）〗 generation rate and the H2O2 content reached the maximum after treated for 3 and 7 hours, respectively, and the MDA content and LOX activity increased with treating time. Cd stress altered the fatty acid composition of
Malus hupehensis via the inducement of reactive oxygen species and lipoxygenase, and induced lipid peroxidation, which was caused by both ROS and LOX within the first 12 hours of CdCl2 treatment and mainly by the increase of LOX activity since then.