AUTHOR=An Dahee , Kim Hyojin , Ju Seulgi , Go Young Sam , Kim Hyun Uk , Suh Mi Chung 

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

JOURNAL=Frontiers in Plant Science

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2017.00034

DOI=10.3389/fpls.2017.00034

ISSN=1664-462X

ABSTRACT=<p>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 <italic>WRINKLED1</italic> (<italic>WRI1</italic>) gene is a well-established key transcriptional regulator involved in the upregulation of fatty acid biosynthesis in developing seeds. WRI1s from <italic>Arabidopsis</italic> 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 <italic>CsWRI1</italic> genes (<italic>CsWRI1A. B</italic>, and <italic>C</italic>) from the <italic>Camelina</italic> oil crop and tested their ability to induce TAG synthesis in leaves. The amino acid sequences of <italic>CsWRI1s</italic> exhibited more than 90% identity with those of <italic>Arabidopsis WRI1</italic>. The transcript levels of the three <italic>CsWRI1</italic> genes showed higher expression levels in developing seeds than in vegetative and floral tissues. When the <italic>CsWRI1A. B</italic>, or <italic>C</italic> was introduced into <italic>Arabidopsis wri1-3</italic> 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 <italic>wri1-3</italic> mutant line. In addition, the fluorescent signals of the enhanced yellow fluorescent protein (eYFP) fused to the <italic>CsWRI1</italic> genes were observed in the nuclei of <italic>Nicotiana benthamiana</italic> leaf epidermal cells. Nile red staining indicated that the transient expression of <italic>CsWRI1A. B</italic>, or <italic>C</italic> caused an enhanced accumulation of oil bodies in <italic>N. benthamiana</italic> leaves. The levels of TAGs was higher by approximately 2.5- to 4.0-fold in <italic>N. benthamiana</italic> fresh leaves expressing <italic>CsWRI1</italic> genes than in the control leaves. These results suggest that the three <italic>Camelina</italic> WRI1s can be used as key transcriptional regulators to increase fatty acids in biomass.</p>