Abstract: 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 sig⁃
nificantly 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 unsaturat⁃
ed fatty acids contents significantly increased. Conversely, in BnaC.FATB.a and BnaA.FATB.b transgenic lines, sat⁃
urated fatty acids contents were significantly increased, and unsaturated fatty acids content was significantly de⁃
creased. The above results indicated that expression of these 5 FAT genes could increase oil content, and modify fat⁃
ty acid composition in transgenic Arabidopsis seeds.

Key words: Brassica napus, fatty acyl-ACP thioesterase, heterologous expression, oil content, fatty acid
composition, RT-qPCR