WRINKLED Transcription Factors Orchestrate Tissue-Specific Regulation of Fatty Acid Biosynthesis in Arabidopsis  

Abstract

Acyl lipids are essential constituents of all cells, but acyl chain requirements vary greatly and depend on the cell type considered. This implies a tight regulation of fatty acid production so that supply fits demand. Isolation of the Arabidopsis thaliana WRINKLED1 (WRI1) transcription factor established the importance of transcriptional regulation for modulating the rate of acyl chain production. Here, we report the isolation of two additional regulators of the fatty acid biosynthetic pathway, WRI3 and WRI4, which are closely related to WRI1 and belong to the APETALA2-ethylene-responsive element binding protein family of transcription factors. These three WRIs define a family of regulators capable of triggering sustained rates of acyl chain synthesis. However, expression patterns of the three WRIs differ markedly. Whereas only WRI1 activates fatty acid biosynthesis in seeds for triacylglycerol production, the three WRIs are required in floral tissues to provide acyl chains for cutin biosynthesis and prevent adherence of these developing organs and subsequent semisterility. The targets of these WRIs encode enzymes providing precursors (acyl chain and glycerol backbones) for various lipid biosynthetic pathways, but not the subsequent lipid-assembling enzymes. These results provide insights into the developmental regulation of fatty acid production in plants.

Multigene Engineering of Triacylglycerol Metabolism Boosts Seed Oil Content in Arabidopsis

“…3). This finding is consistent with other studies that suggest that WRI1 is not a significant regulator of DGAT1 expression (Baud et al, 2007;To et al, 2012).…”

“…Previous studies have shown that overexpression of the WRI1 transcription factor activates the expression of multiple genes associated with lower glycolysis and fatty acid synthesis (Baud et al, 2007;To et al, 2012) and can enhance oil content in seeds of Arabidopsis (Cernac and Benning, 2004). However, WRI1 has little influence over the expression of genes involved in TAG assembly and packaging (Baud et al, 2007;To et al, 2012). The key enzyme responsible for TAG assembly is encoded by DGAT1 (Katavic et al, 1995;Zhang et al, 2009), and overexpression of this gene can also enhance seed oil content (Jako et al, 2001).…”

“…Overexpression of WRI1 or DGAT1 has been reported to increase seed oil content (Jako et al, 2001;Cernac and Benning, 2004). However, WRI1 predominantly targets the expression of genes associated with glycolysis and fatty acid synthesis (Baud et al, 2007;To et al, 2012), while DGAT1 catalyzes the final step in the assembly of TAG from DAG and acyl-CoA (Katavic et al, 1995). Top-down metabolic control analysis studies suggest that a significant proportion of control over TAG synthesis lies within both portions of the metabolic pathway (Weselake et al, 2008;Tang et al, 2012).…”

Arabidopsis BPM Proteins Function as Substrate Adaptors to a CULLIN3-Based E3 Ligase to Affect Fatty Acid Metabolism in Plants

“…The fact that overall metabolic changes were mostly restricted to total fatty acid contents also indicates that the function of BPM proteins in seeds is strongly connected with WRI1 activity. In this context, it is of note that WRI1 has very recently been described as part of a small gene family with a total of four members in Arabidopsis (To et al, 2012). Although WRI1 is the primary member that regulates fatty acid biosynthesis in seeds, the other members also contribute to this pathway, but they do so in other tissues (To et al, 2012).…”

Using modern plant breeding to improve the nutritional and technological qualities of oil crops

“…One example is where a mutation of the PKL (PICKLE) gene led to the upregulation of a variety of transcription factor genes involved in embryo development and the induction of lipid droplet formation in leaf cells (Ogas et al, 1997). Other examples have focused on one of the downstream transcription factor genes from PKL called WRI1 (WRINKLED1) which is involved in the upregulation of parts of the glycolysis and fatty acid biosynthesis pathways that generate the acyl components required for TAG assembly and accumulation (Ma et al, 2013;To et al, 2012).…”