Seed-Specific Over-Expression of an Arabidopsis cDNA Encoding a Diacylglycerol Acyltransferase Enhances Seed Oil Content and Seed Weight

Jako, Colette; Kumar, Arvind; Wei, Yangdou; Zou, Jitao; Barton, Dennis L.; Giblin, E. Michael; Covello, Patrick S.; Taylor, David C.

doi:10.1104/pp.126.2.861

Cited by 458 publications

(397 citation statements)

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“…This enzyme catalyzes the terminal step in the pathway for TAG synthesis, one in which a fatty acid is added through an ester linkage to the sn-3 carbon of DAG (Hobbs and Hills, 2000). It is the only enzyme in this pathway unique to TAG synthesis (Bao and Ohlrogge, 1999) and has been shown to be rate limiting (Jako et al, 2001). The increase in DGAT1 transcript levels was ascertained by probing northern blots of total RNA with E6B2T7, an EST clone that has been annotated as DGAT1.…”

Section: Discussionmentioning

confidence: 99%

“…Much of the characterization of this gene to date has been focused on determining its effect on seed oil accumulation and the fatty acid composition of TAG in seed oil. To this end, seed-specific mutants have been analyzed (Katavic et al, 1995;Zou et al, 1999;Jako et al, 2001), and among the findings from these studies is the fact that dysfunctional DGAT1 protein results in a decrease in stored TAG and altered TAG fatty acid composition (Katavic et al, 1995). Overexpression of DGAT1 in Arabidopsis seeds engenders an increase in seed size and oil content, suggesting that DGAT catalyzes the ratelimiting step in TAG biosynthesis (Jako et al, 2001).…”

mentioning

confidence: 99%

“…To this end, seed-specific mutants have been analyzed (Katavic et al, 1995;Zou et al, 1999;Jako et al, 2001), and among the findings from these studies is the fact that dysfunctional DGAT1 protein results in a decrease in stored TAG and altered TAG fatty acid composition (Katavic et al, 1995). Overexpression of DGAT1 in Arabidopsis seeds engenders an increase in seed size and oil content, suggesting that DGAT catalyzes the ratelimiting step in TAG biosynthesis (Jako et al, 2001). In addition, Routaboul et al (1999) have demonstrated that when Arabidopsis DGAT1 is inactivated through a frame-shift mutation, seeds are still produced indicating that proteins other than DGAT1 are able to catalyze TAG formation.…”

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A Role for Diacylglycerol Acyltransferase during Leaf Senescence

2002

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Lipid analysis of rosette leaves from Arabidopsis has revealed an accumulation of triacylglycerol (TAG) with advancing leaf senescence coincident with an increase in the abundance and size of plastoglobuli. The terminal step in the biosynthesis of TAG in Arabidopsis is catalyzed by diacylglycerol acyltransferase 1 (DGAT1; EC 2.3.1.20). When gel blots of RNA isolated from rosette leaves at various stages of development were probed with the Arabidopsis expressed sequence tag clone, E6B2T7, which has been annotated as DGAT1, a steep increase in DGAT1 transcript levels was evident in the senescing leaves coincident with the accumulation of TAG. The increase in DGAT1 transcript correlated temporally with enhanced levels of DGAT1 protein detected immunologically. Two lines of evidence indicated that the TAG of senescing leaves is synthesized in chloroplasts and sequesters fatty acids released from the catabolism of thylakoid galactolipids. First, TAG isolated from senescing leaves proved to be enriched in hexadecatrienoic acid (16:3) and linolenic acid (18:3), which are normally present in thylakoid galactolipids. Second, DGAT1 protein in senescing leaves was found to be associated with chloroplast membranes. These findings collectively indicate that diacylglycerol acyltransferase plays a role in senescence by sequestering fatty acids de-esterified from galactolipids into TAG. This would appear to be an intermediate step in the conversion of thylakoid fatty acids to phloem-mobile sucrose during leaf senescence.Diacylglycerol (DAG) acyltransferase (DGAT; EC 2.3.1.20) mediates the final acylation step in the synthesis of triacylglycerol (TAG). It is present in most plant organs, including leaves, petals, fruits, anthers, and developing seeds (Hobbs et al., 1999). In seeds, TAG is thought to be synthesized within the membranes of the endoplasmic reticulum and subsequently released into the cytosol in the form of oil bodies, which bleb from the cytoplasmic surface of the endoplasmic reticulum (Huang, 1992). The stored TAG is localized in the interior of the oil body, and the surfaces of oil bodies are coated with a monolayer of phospholipid associated with oleosin, the major protein of oil bodies. The acyl chains of the phospholipid monolayer are embedded in the TAG interior of the oil body. Oleosin is a structural protein that is thought to prevent coalescence of oil bodies during seed dehydration (Huang, 1996). That oil bodies originate from the endoplasmic reticulum is consistent with the finding that enzymes of TAG synthesis, including DGAT, are present in microsomal membrane fractions, which are known to contain vesicles of endoplasmic reticulum (Kwanyuen and Wilson, 1986). In addition, TAG can be synthesized in vitro in the presence of microsomes isolated from developing seeds (Lacey et al., 1999).Although TAG formation in seeds is believed to occur in the ER, there have been several reports indicating that purified chloroplast envelope membranes from leaves are also capable of synthesizing this storage lipid (Siebe...

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Section: Discussionmentioning

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A Role for Diacylglycerol Acyltransferase during Leaf Senescence

2002

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“…DGAT1, which catalyzes the final acylation step of sn-1,2-diacylglycerol to TAG, is thought to be the ratelimiting enzyme of TAG biosynthesis (Ichihara et al, 1988). Arabidopsis dgat1 mutant seeds only accumulate about 55% to 75% of TAG (Routaboul et al, 1999;Zou et al, 1999;Kaup et al, 2002), whereas seedspecific overexpression of DGAT1 increases oil content from 11% to 28% (Jako et al, 2001;Taylor et al, 2009;Andrianov et al, 2010). DGAT1 is also important for TAG accumulation in leaves (Slocombe et al, 2009).…”

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ABI4 Activates DGAT1 Expression in Arabidopsis Seedlings during Nitrogen Deficiency

et al. 2011

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Triacylglycerol (TAG) is the major seed storage lipid and is important for biofuel and other renewable chemical uses. Acylcoenzyme A:diacylglycerol acyltransferase1 (DGAT1) is the rate-limiting enzyme in the TAG biosynthesis pathway, but the mechanism of its regulation is unknown. Here, we show that TAG accumulation in Arabidopsis (Arabidopsis thaliana) seedlings increased significantly during nitrogen deprivation (0.1 mM nitrogen) with concomitant induction of genes involved in TAG biosynthesis and accumulation, such as DGAT1 and OLEOSIN1. Nitrogen-deficient seedlings were used to determine the key factors contributing to ectopic TAG accumulation in vegetative tissues. Under low-nitrogen conditions, the phytohormone abscisic acid plays a crucial role in promoting TAG accumulation in Arabidopsis seedlings. Yeast one-hybrid and electrophoretic mobility shift assays demonstrated that ABSCISIC ACID INSENSITIVE4 (ABI4), an important transcriptional factor in the abscisic acid signaling pathway, bound directly to the CE1-like elements (CACCG) present in DGAT1 promoters. Genetic studies also revealed that TAG accumulation and DGAT1 expression were reduced in the abi4 mutant. Taken together, our results indicate that abscisic acid signaling is part of the regulatory machinery governing TAG ectopic accumulation and that ABI4 is essential for the activation of DGAT1 in Arabidopsis seedlings during nitrogen deficiency.

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“…La modification de l'abondance de cette enzyme dans les graines oléagineuses en cours de maturation pourrait conduire à des modifications intéressantes de la teneur en huile et/ou de la nature des huiles [26]. La caractérisation du gène codant pour la DGAT permet donc d'envisager son utilisation comme marqueur moléculaire ou transgène pour l'amélioration des plantes ou des microorganismes, afin de produire des huiles dédiées aux différentes utilisations industrielles et alimentaires.…”

Section: Mutant De Synthèse De Réserves Lipidiquesunclassified

NORD : IMPACTS DES BIOTECHNOLOGIES RECHERCHES Approches moléculaires de la qualité et du développement des graines

Dubreucq¹,

Grappin²,

Miquel³

et al. 2001

OCL

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Résumé :Les semences constituent le maillon essentiel de la production végétale car elles sont à la fois le vecteur de la multiplication des plantes et la source de denrées alimentaires. L'agriculture moderne exige le respect des critères de qualité des semences qui ne sont évidemment pas les mêmes suivant que l'utilisation des semences sera alimentaire, industrielle ou de simple semis. Du point de vue alimentaire ou industriel, la qualité se définit en fonction de la nature et du rendement de l'extraction du produit d'intérêt. Lorsque la graine est utilisée comme semence, la qualité est appréciée suivant des critères qui sont la conformité génétique, l'état sanitaire et la capacité germinative. Les normes qualitatives alors retenues concourent à l'obtention de peuplements homogènes et vigoureux. La semence idéale doit évidemment combiner ces différents critères de qualité. Les bases biologiques qui sous-tendent la plupart des critères de qualité sont encore très mal connues et leur élucidation demeure un défi scientifique majeur. Summary : Seeds are essential for plant propagation and crop production and must satisfy the increasingly diverse requirements of both modern agriculture and the agro-industry. The biological bases of seed quality are still poorly understood. Progress in this area will no doubt emerge from the identification of genes that control quality parameters, through the tremendous advances made using genomic based techniques. In this way, the use of 50,000 Arabidopsis thaliana T-DNA mutant lines, developed in France, at the Inra Versailles has enabled us to isolate genes whose functions are essential for seed development and maturation, e.g. storage compound synthesis and deposition, and tegument composition. Mutants have been isolated that are either strongly impaired in protein glycosylation (glycosidase I mutant) or whose lipid composition is modified (diacylglycerol acyltransferase: DGAT mutant). The corresponding cloned genes should prove useful in biotechnological applications for the reduction of the allergenicity of engineered proteins produced in plants and for modifying seed lipid composition respectively. New Transparent Testa genes have also been obtained that play a role in the control of pigment deposition in the seed testa. Engineering the composition of seed coats is a real challenge for the improvement of the nutritional value of seeds for animal feeding. The zeaxanthin epoxidase gene has been cloned, as this is required for the biosynthesis of the hormone abscisic acid (ABA). Using this gene it has been possible to Article disponible sur le site http://www.ocl-journal.org ou http://dx

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Seed-Specific Over-Expression of an Arabidopsis cDNA Encoding a Diacylglycerol Acyltransferase Enhances Seed Oil Content and Seed Weight

Cited by 458 publications

References 58 publications

A Role for Diacylglycerol Acyltransferase during Leaf Senescence

A Role for Diacylglycerol Acyltransferase during Leaf Senescence

ABI4 Activates DGAT1 Expression in Arabidopsis Seedlings during Nitrogen Deficiency

NORD : IMPACTS DES BIOTECHNOLOGIES RECHERCHES Approches moléculaires de la qualité et du développement des graines

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