甘蓝型油菜中5个脂酰-ACP硫酯酶基因的克隆与功能初步分析

Gene isolation and characterization of 5 fatty acyl-ACP thioesterase in Brassica napus

为了解影响油菜种子含油量的关键基因,从高含油量(HO)和低含油量(LO)甘蓝型油菜中克隆了5个脂酰-ACP硫酯酶(fatty acyl-ACP thioesterase, FAT)的基因。序列分析表明这5个FAT基因在HO和LO油菜基因组之间没有序列差异。5个FAT基因分别命名为:BnaA.FATA.a、BnaC.FATA.b、BnaA.FATA.c、BnaC.FATB.a和BnaA.FATB.b。分析表明,HO种子中5个FAT基因的表达水平显著高于LO种子。异源表达结果显示,5个FAT基因的所有酵母转化子的含油量均显著增加,并且它们的脂肪酸组成均发生了变化。将这5个FAT基因转化到拟南芥中进行进一步的功能分析。5个转基因材料T1种子含油量均显著增加;BnaA.FATA.a、BnaC.FATA.b、BnaA.FATA.c转基因株系中的饱和脂肪酸含量显著降低,而不饱和脂肪酸含量均显著增加;相反,在BnaC.FATB.a和BnaA.FATB.b转基因材料中,饱和脂肪酸含量显著增加,而不饱和脂肪酸含量显著降低。结果表明,这5个FAT基因不仅可以增加拟南芥含油量,而且可以改变脂肪酸组成比例。

To better understand FAT gene function which encodes fatty acyl-ACP thioesterase, 5 FAT genes were cloned from Brassica napus cultivars with high oil content(HO) and low oil content(LO). They were named as BnaA.FATA.a, BnaC.FATA.b, BnaA.FATA.c, BnaC.FATB.a and BnaA.FATB.b. No sequence difference was found in these 5 genes between HO and LO. RT-qPCR analyses showed that expression levels of them in HO seeds were significantly higher than those in LO seeds. Yeast heterologous expression of them showed that oil content of all yeast transformants were significantly increased, and their fatty acid composition were modified. After transformed into Arabidopsis, seeds oil of all T1 transgenic lines were significantly increased. The saturated fatty acids contents in 3 lines(BnaA.FATA.a, BnaC.FATA.b and BnaA.FATA.c transgenic lines) were significantly decreased, with unsaturated fatty acids contents significantly increased. Conversely, in BnaC.FATB.a and BnaA.FATB.b transgenic lines, saturated fatty acids contents were significantly increased, and unsaturated fatty acids content was significantly decreased. The above results indicated that expression of these 5 FAT genes could increase oil content, and modify fatty acid composition in transgenic Arabidopsis seeds.