Using DGAT1, SLC, FAD2and FAD3Gene To Modify Oil Content And Fatty Acid Unsaturation Of Arabidopsis Thaliana And Brassica Napus

Rapeseed is one of the four major oil crops in the world, it is not only the mostimportant source of edible vegetable oil, but also the ideal raw material for biodiesel. Itbecomes a goal for many scientists to improve oil content of rapeseed. In the synthesis ofthe triacylglycerol TAG, Diacylglycerol acyltransferase (DGAT1) is a rate-limiting enzymecatalyzed the final step.Yeast sn-2acyltransferase SLC is a lysophosphatidic acidacyltransferase, it can catalyze lysophospholipids acid to form phosphatidic acid, whichmay change the total fatty acid content and composition.18-carbon unsaturated fatty acids of rape seed oil mainly include oleic acid (18:1),linoleic acid (18:2) and linolenic acid (18:3). Since the human body can not synthesize18:2and18:3, both are called essential fatty acids. Biosynthesis of essential fatty acids18:2and18:3in plants has been paid much attention by researchers. Oleic acid desaturase (Fatty aciddesaturase2, FAD2) introduce the second double bond for monounsaturated fatty acids, itcontrols the first and key step in the synthesis of polyunsaturated fatty acids. Linoleic aciddesaturase (Fatty acid desaturase3, FAD3) catalyze the synthesis of linolenic acid. In rapeseeds, these two genes play an important roles for changing unsaturated fatty acids content.Previous studies have shown that overexpressing Tropaeolum majus DGAT1(TmDGAT1) and yeast SLC can increase oil contents respectively. OverexpressingTropaeolum majus FAD2(TmFAD2) can increase linoleic acid (18:2) content. Andoverexpressing Brassic napus FAD3(BnFAD3) can increase linolenic acid (18:3) content. Inthis study, using TmDGAT and yeast SLC,we expect to improve the content of rape seed oiland explore oil accumulation in vegetative organs; Using TmFAD2and BnFAD3,we expectto improve the content of unsaturated fatty acids in rape seed and explore the influence ofthe unsaturated fatty acid accumulation in vegetative organs for plant resistance. Weobtained the following results:(1) We successfully constructed double-gene plant expression vector pSDS whichcombined TmDGAT1and SLC and double-gene plant expression vector pSFF whichcombined TmFAD2and BnFAD3.(2) Using Agrobacterium-mediated floral dip method, we transformed vector pSDS and pSFF into Arabidopsis thaliana Columbia wild-type and obtained11and19transgeniclines respectively. We performed preliminary observation on the transgenic plantsphenotype. In pSFF transgenic lines, it was discovered that the first pair of true leaf on theT1transgenic plants showed different levels of deformity. According to the degree ofdeformity, the transgenic plants were divided into four grades.The leaves and seeds fattyacid compositions and contents of transgenic plants showed that the more serious deformity,the more obvious decrease of C18:3. In pSDS transgenic lines, it was discovered that oilcontents have significantly increased by10%~60%in some T2heterozygous seeds.(3) Using Agrobacterium-mediated floral-dip method, pSDS and pSFF weretransformed into Brassica napus "12-1601"and obtained25and26transgenic lines,respectively. Phenotype and fatty acid contents were investigated on the transgenic plants.In pSDS transgenic lines, results showed that the oil content have not increased in T2heterozygous seeds.