ABSTRACT
Enhancing soybean (Glycine max) oil production is crucial to meet the market demand of vegetable oil. Diacylglycerol acyltransferase (DGAT) catalyzes the final acylation reaction of triacylglycerol (TAG) synthesis, acting as one of the rate-limiting enzymes for oil biosynthesis in plant seeds. Here, a cDNA clone VgDGAT1A encoding the DGAT1 protein was isolated from the high oil plant Vernonia galamensis. VgDGAT1A was specifically overexpressed in soybean seeds, and several high-generation transgenic lines (T7) were obtained by continuous selection. qPCR analysis showed that VgDGAT1A was highly expressed in the mid-development stage (30-45 DAF) of the transgenic seeds. Accordingly, the DGAT enzyme activity in the transgenic seeds was increased by 7.8 folds in comparison with the wild-type controls. Seed oil and starch contents were, respectively, increased by 5.1% (Dry weight) and reduced by 2%-3% in the transgenic soybeans. Importantly, protein content was not significantly different between transgenic and control seeds. Seed weight and germination rate of the transgenic lines exhibited no negative effect. Fatty acid profiling demonstrated that antioxidant oleic acid (C18:1Δ9) content in the transgenic seed oil was elevated by 8.2% compared to the control, and correspondingly, easily-oxidized linoleic acid (C18:2Δ9,12) and linolenic acid (C18:3Δ9,12,15) were decreased by 6% and 2% respectively. Taken together, seed-specific overexpression of an exogenous VgDGAT1A gene can break the negative linkage of oil and protein contents in soybean seeds, indicating that engineering of this highly-active DGAT enzyme is an effective strategy to improve oil yield and nutritional value in oilseeds.
ABSTRACT
Objective To examine the effect of Pu-Erh tea extract(PTE) on genes expression of lipogenesis in white adipose tissue of rats fed high fat diet.Method Thirty male SD rats were randomly divided into three groups(n=10):the control group(basal diet);the high fat group(high fat diet);the PTE group(high fat diet + Pu-Erh tea extract).Body weight and adipose tissue were measured.Expression of genes regulating lipid metabolism was assessed in adipose tissue.Results PTE supplementation prevented diet-induced increases in body weight and adipose tissue.Diacylglycerol acyltransferase-1(DGAT1),stearoyl-CoA desalurase-1(SCD1) and sterol regulatory element binding protein-1c(SREBP-1c) mRNA levels were markedly decreased in adipose tissue of rats fed PTE.Conclusion This study shows for the first time that Pu-Erh tea extract prevents diet-induced obesity,and this effect is partly mediated via a direct influence on adipose tissue.