A phenylalanine in DGAT is a key determinant of oil content and composition in maize

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Nature Genetics (Impact Factor: 29.35). 04/2008; 40(3):367-72. DOI: 10.1038/ng.85
Source: PubMed

ABSTRACT Plant oil is an important renewable resource for biodiesel production and for dietary consumption by humans and livestock. Through genetic mapping of the oil trait in plants, studies have reported multiple quantitative trait loci (QTLs) with small effects, but the molecular basis of oil QTLs remains largely unknown. Here we show that a high-oil QTL (qHO6) affecting maize seed oil and oleic-acid contents encodes an acyl-CoA:diacylglycerol acyltransferase (DGAT1-2), which catalyzes the final step of oil synthesis. We further show that a phenylalanine insertion in DGAT1-2 at position 469 (F469) is responsible for the increased oil and oleic-acid contents. The DGAT1-2 allele with F469 is ancestral, whereas the allele without F469 is a more recent mutant selected by domestication or breeding. Ectopic expression of the high-oil DGAT1-2 allele increases oil and oleic-acid contents by up to 41% and 107%, respectively. This work provides insights into the molecular basis of natural variation of oil and oleic-acid contents in plants and highlights DGAT as a promising target for increasing oil and oleic-acid contents in other crops.

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Available from: Victor Llaca, Sep 29, 2015
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    • "Accordingly, Arabidopsis dgat1 mutants have reduced seed oil content (Katavic et al., 1995; Zou et al., 1999), and the overexpression of Arabidopsis DGAT1 and the maize high-oil DGAT1-2 allele increases the oil content of Arabidopsis and maize seeds, respectively (Jako et al., 2001; Zheng et al., 2008). An alternative to up-regulating the expression of rate-limiting enzymes in the metabolic pathways responsible for the accumulation of seed oil involves the manipulation of genes that encode master regulators of the complex transcriptional networks that coordinate seed development. "
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    ABSTRACT: The synthesis of fatty acids and glycerolipids in wild-type Arabidopsis leaves does not typically lead to strong triacylglycerol (TAG) accumulation. LEAFY COTYLEDON2 (LEC2) is a master regulator of seed maturation and oil accumulation in seeds. Constitutive ectopic LEC2 expression causes somatic embryogenesis and defects in seedling growth. Here, we report that senescence-inducible LEC2 expression caused a threefold increase in TAG levels in transgenic leaves compared with that in the leaves of wild-type plants. Plant growth was not severely affected by the accumulation the TAG in response to LEC2 expression. The levels of plastid-synthesized lipids, mono- and di-galactosyldiacylglycerol and phosphatidylglycerol were reduced more in senescence-induced LEC2 than in endoplasmic reticulum-synthesized lipids, including phosphatidylcholine, phosphatidylethanolamine and phosphatidylinositol. Senescence-induced LEC2 up-regulated the expression of many genes involved in fatty acid and TAG biosynthesis at precise times in senescent leaves, including WRINKLED1 (WRI1), which encodes a fatty acid transcription factor. The expressions of glycerol-3-phosphate dehydrogenase 1 and phospholipid:diacylglycerol 2 were increased in the transgenic leaves. Five seed-type oleosin-encoding genes, expressed during oil-body formation, and the seed-specific FAE1 gene, which encodes the enzyme responsible for the synthesis of C20:1 and C22:1 fatty acids, were also expressed at higher levels in senescing transgenic leaves than in wild-type leaves. Senescence-inducible LEC2 triggers the key metabolic steps that increase TAG accumulation in vegetative tissues. © 2015 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.
    Plant Biotechnology Journal 03/2015; DOI:10.1111/pbi.12354 · 5.75 Impact Factor
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    • "DGAT1 and DGAT2 are localized in the endoplasmic reticulum (ER; Zou et al. 1999; Lardizabal et al. 2001; Shockey et al. 2006). Arabidopsis DGAT1 is strongly involved in regulating the seed oil content in plants that do not produce UFAs (Zou et al. 1999; Jako et al. 2001; Zheng et al. 2008). DGAT2 from some UFA-producing plants plays an important role in the accumulation of UFAs in TAG (Kroon et al. 2006). "
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    ABSTRACT: Key message Hydroxy fatty acids produced in plant seed oil are important industrial material. This review focuses on the use of metabolic engineering approaches for the production of hydroxy fatty acids in transgenic plants. Abstract Vegetable oil is not only edible but can also be used for industrial purposes. The industrial demand for vegetable oil will increase with the continued depletion of fossil fuels and ensuing environmental issues such as climate change, caused by increased carbon dioxide in the air. Some plants accumulate high levels of unusual fatty acids in their seeds, and these fatty acids (FAs) have properties that make them suitable for industrial applications. Hydroxy fatty acids (HFAs) are some of the most important of these industrial FAs. Castor oil is the conventional source of HFA. However, due to the presence of toxin ricin in its seeds, castor is not cultivated on a large scale. Lesquerella is another HFA accumulator and is currently being developed as a new crop for a safe source of HFAs. The mechanisms of HFA synthesis and accumulation have been extensively studied using castor genes and the model plant Arabidopsis. HFAs accumulated to 17 % in the seed oil of Arabidopsis expressing a FA hydroxylase gene from castor (RcFAH12), but its seed oil content and plant growth decreased. When RcFAH12 gene was coexpressed with additional castor gene(s) in Arabidopsis, ~30 % HFAs were accumulated and the seed oil content and plant growth was almost restored to the wild-type level. Further advancement of our understanding of pathways, genes and regulatory mechanisms underlying synthesis and accumulation of HFAs is essential to developing and implementing effective genetic approaches for enhancing HFA production in oilseeds.
    Plant Cell Reports 01/2015; 34(4). DOI:10.1007/s00299-015-1736-6 · 3.07 Impact Factor
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    • "Seed-specific over-expression of the DGAT coding region in wild type Arabidopsis enhanced oil deposition 9%–12% and average seed weight in a manner that correlated with DGAT transcript levels (Jako et al., 2001). Expression of the maize PH09B DGAT1-2 allele (normal oil content) under the oleosin promoter led to an average increase of 9.3% seed oil content, while expression of the ASKC28IB1 DGAT1-2 allele (high oil content) led to an average increase of 27.9% (Zheng et al., 2008). Over-expression of TmDGAT1 from nasturtium (Tropaeolum majus) in wild type Arabidopsis and high-erucic-acid rapeseed (HEAR) B. napus resulted in a 3.5%–10% increase in oil content on a dry weight basis (Xu et al., 2008). "
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    ABSTRACT: Oilseed rape (Brassica napus) is one of the most important oilseed crops globally. To meet increasing demand for oil-based products, the ability to enhance desirable oil content in the seed is required. This study assessed the capability of five genes in the triacylglyceride (TAG) synthesis pathway to enhance oil content. The genes BnGPDH, BnGPAT, BnDGAT, ScGPDH and ScLPAAT were overexpressed separately in a tobacco (Nicotiana benthamiana) model system, and simultaneously by pyramiding in B. napus, under the control of a seed specific Napin promoter. ScLPAAT transgenic plants showed a significant increase of 6.84% to 8.55% in oil content in tobacco seeds, while a ~4% increase was noted for BnGPDH and BnGPAT transgenic seeds. Seed-specific overexpression of all four genes in B. napus resulted in as high a 12.57% to 14.46% increased in seed oil content when compared to WT, equaling close to the sum of the single-gene overexpression increases in tobacco. Taken together, our study demonstrates that BnGPDH, BnGPAT and ScLPAAT may effectively increase seed oil content, and that simultaneous overexpression of these in transgenic B. napus may further enhance the desirable oil content relative to single-gene overexpressors. Copyright © 2014. Published by Elsevier B.V.
    Gene 12/2014; 557(2). DOI:10.1016/j.gene.2014.12.029 · 2.14 Impact Factor
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