采用气相色谱法和 SDS - PAGE 电泳法研究了经过 50 ~ 150 mmol· L ^{- 1} NaCl 胁迫处理后构树〔 Broussonetiapapyrifera (L.) L’Hérit. ex Vent.〕组培苗根和叶片内质网膜脂肪酸和蛋白质组成的变化。 结果表明,构树根和叶片内质网膜脂肪酸组成差异较大,但均为不饱和脂肪酸相对含量较高;脂肪酸基本成分为棕榈酸、硬脂酸、棕榈油酸、油酸、亚油酸及反亚油酸,但根中还含花生酸、山萮酸、木蜡酸、亚麻酸和二十碳二烯酸,叶片中还含反油酸;根中的不饱和脂肪酸指数(IUFA)大于叶片。 不同浓度 NaCl 胁迫对构树组培苗根和叶片内质网膜脂肪酸组成和蛋白质组成均有一定的影响。 在 NaCl 胁迫条件下,根内质网膜饱和脂肪酸相对含量呈增加趋势,不饱和脂肪酸相对含量趋于减少,且随着 NaCl 浓度的提高,IUFA 逐渐降低;叶片内质网膜中各脂肪酸成分相对含量的变化趋势各异,但在低浓度 NaCl 条件下,IUFA 较对照有所提高,随 NaCl 浓度的升高 IUFA 又低于对照,且叶片内质网膜 IUFA 的降幅小于根。 根和叶片内质网膜中蛋白质组成明显不同;不同浓度 NaCl 胁迫除对内质网膜各蛋白质组分表达量有一定影响外,还导致根中相对分子质量 70 000 的蛋白质条带消失,叶片中则出现了相对分子质量 95 000 的新蛋白质条带。

 

Changes of fatty acid and protein composition of endoplasmic reticulum ( ER) membrane in root and leaf of Broussonetia papyrifera (L.) L’ Hérit. ex Vent. plantlets at stress condition of 50 – 150 mmol· L ^{- 1} NaCl were studied by gas chromatography and SDS-PAGE electrophoresis. The results show that there are obvious differences in fatty acid composition of ER membrane in root and leaf, but the relative content of unsaturated fatty acids in both of them is higher. The fatty acid composition is mainly consisted of palmitic acid, stearic acid, palmitoleic acid, oleic acid, linoleic acid and linolelaidic acid, and there are also arachidic acid, behenic acid, lignoceric acid, linolenic acid and cis-11, 14- eicosadienoic acid in root and elaidic acid in leaf. The index of unsaturated fatty acids (IUFA) is higher in root than in leaf. NaCl stress has a certain influence on fatty acid and protein compositions of ER membrane in root and leaf of B. papyrifera plantlets. In root, the relative content of saturated fatty acids of ER membrane increases, while the relative content of unsaturated fatty acids decreases, and the IUFA decreases gradually with the increase of NaCl concentration. In leaf, the variation trend of relative content of each fatty acid varies, the IUFA of ER membrane under low NaCl concentration is higher than that of the control, and then declines with the increase of NaCl concentration. Moreover, the decrease range of IUFA in root is greater than that in leaf. Protein composition of ER membrane in root and leaf is obviously different. NaCl stress with different concentrations not only has an effect on the expression amount of proteins in ER membrane, but also lead to the protein band with a relative molecular weight of 70 000 in root disappearing and a new protein band with a relative molecular weight of 95 000 in leaf appearing.