Expression of Camelina WRINKLED1 Isoforms Rescue the Seed Phenotype of the Arabidopsis wri1 Mutant and Increase the Triacylglycerol Content in Tobacco Leaves

Triacylglycerol (TAG) is an energy-rich reserve in plant seeds that is composed of glycerol esters with three fatty acids. Since TAG can be used as a feedstock for the production of biofuels and bio-chemicals, producing TAGs in vegetative tissue is an alternative way of meeting the increasing demand for its usage. The ( ) gene is a well-established key transcriptional regulator involved in the upregulation of fatty acid biosynthesis in developing seeds. WRI1s from and several other crops have been previously employed for increasing TAGs in seed and vegetative tissues. In the present study, we first identified three functional genes ( , and ) from the oil crop and tested their ability to induce TAG synthesis in leaves. The amino acid sequences of exhibited more than 90% identity with those of . The transcript levels of the three genes showed higher expression levels in developing seeds than in vegetative and floral tissues. When the , or was introduced into loss-of-function mutant, the fatty acid content was restored to near wild-type levels and percentages of the wrinkled seeds were remarkably reduced in the transgenic lines relative to mutant line. In addition, the fluorescent signals of the enhanced yellow fluorescent protein (eYFP) fused to the genes were observed in the nuclei of leaf epidermal cells. Nile red staining indicated that the transient expression of , or caused an enhanced accumulation of oil bodies in leaves. The levels of TAGs was higher by approximately 2.5- to 4.0-fold in fresh leaves expressing genes than in the control leaves. These results suggest that the three WRI1s can be used as key transcriptional regulators to increase fatty acids in biomass.