C-Terminal Region of WRI1 Paralogs in Avocado Is a Potential Target for Oil Enhancement in Nonseed Tissues

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WRINKLED1 (WRI1), a member of AP2/EREBP class of transcription factors regulates carbon allocation between glycolytic and fatty acid biosynthetic pathway in plants. Additionally, among the four WRI1 paralogs in arabidopsis, WRI3 and 4 but not WRI2, are also able to increase fatty acid content in seed tissue. While the role of WRI1 is well established in seeds, the potential role of WRI1 or its paralogs as master regulators in oil-rich nonseed tissues is poorly understood. One of the basal angiosperm avocado (Persea americana) accumulates high oil content in its mesocarp throughout its fruit development. Recent transcriptome studies of avocado mesocarp revealed that the ortholog of WRI2, along with WRI1 and WRI3 were highly expressed throughout the developmental stages. Through transient expression assays, we further demonstrated that both PaWRI1 and PaWRI2 can accumulate oil in tobacco leaves. We conducted a comprehensive and comparative in silico analysis of WRI1, 2 & 3 orthologs from A. thaliana (dicot), Z. mays (monocot) and P. americana (basal angiosperm) to identify distinct features associated with function. Our data shows a difference in C-terminal intrinsically disordered region (IDR) and potential phosphorylation sites in PamWRI1 & 2, which might suggest their possible role in high oil biosynthesis in mesocarp tissue. Also, enrichment with hydrophobic amino acid and depletion of hydrophilic amino acid leads to high random coil secondary structure with PamWRI1 &2 showing the highest percentage among all. Absence of C- terminal PEST motif in PamWRI1 & 2 might result in their stability in nonseed tissue and thus leads to high oil biosynthesis and accumulation. These data suggest that variable C-terminal region among the WRI1 orthologs is a potential target to enhance oil biosynthesis in nonseed tissues.


Johnson City, TN

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