The olive DGAT2 gene is developmentally regulated and shares overlapping but distinct expression patterns with DGAT1

Abstract

Diacylglycerol acyltransferases (DGATs) catalyse the final step of the triacylglycerol (TAG) biosynthesis of the Kennedy pathway. Two major gene families have been shown to encode DGATs, DGAT1 (type-1) and DGAT2 (type-2). Both genes encode membrane-bound proteins, with no sequence homology to each other. In this study, the molecular cloning and characterization of a type-2 DGAT cDNA from olive is presented. Southern blot analysis showed that OeDGAT2 is represented by a single copy in the olive genome. Comparative transcriptional analysis revealed that DGAT1 and DGAT2 are developmentally regulated and share an overall overlapping but distinct transcription pattern in various tissues during vegetative growth. DGAT2 is highly expressed in mature or senescing olive tissues. In flowers, the expression of DGAT1 was almost undetectable, while DGAT2 transcripts accumulated at the later stages of both anther and ovary development. Differential gene regulation was also detected in the seed and mesocarp, two drupe compartments that largely differ in their functional roles and mode of lipid accumulation. DGAT1 appears to contribute for most of the TAG deposition in seeds, whereas, in the mesocarp, both DGAT1 and DGAT2 share an overlapping expression pattern. During the last stages of mesocarp growth, when TAGs are still accumulating, strong up-regulation of DGAT2 but a marked decline of DGAT1 transcript levels were detected. The present results show overlapping gene expression for olive DGATs during mesocarp growth, with a more prominent implication of DGAT2 in floral bud development and fruit ripening.

Quantitative trait loci (QTLs) analysis of palm oil fatty acid composition in an interspecific pseudo-backcross from Elaeis oleifera (H.B.K.) Cortés and oil palm (Elaeis guineensis Jacq.)

“…(Wilson et al 2001;Monteros et al 2008;Ha et al 2010;Li et al 2011;Chen et al 2012) and olive (Olea europaea L.) (Poghosyan et al 1999;Hernández et al 2005;Banilas et al 2011). With respect to genes involved in the fatty acid biosynthesis in oil palm, Nakkaew et al (2008) identified and cloned the gene of biotin carboxylase (accD) from E. guineensis which is involved in the first step of the fatty acid synthesis.…”

Altered Lipid Composition and Enhanced Nutritional Value of Arabidopsis Leaves following Introduction of an Algal Diacylglycerol Acyltransferase 2

“…DGAT1 proteins are predicted to possess six or more transmembrane domains and belong to the membrane-bound O-acyltransferase family (Cases et al, 1998). Forward and reverse genetic approaches have confirmed that the Arabidopsis thaliana DGAT1 gene affects the TAG levels in seeds (Routaboul et al, 1999;Zou et al, 1999;Jako et al, 2001), and DGAT1 genes have been studied in detail in several species (Lung and Weselake, 2006;Shockey et al, 2006;Banilas et al, 2011). Structurally, DGAT2 proteins differ from DGAT1 and possess only two to three predicted transmembrane domains (Yen et al, 2008).…”

Characterisation of DGAT1 and DGAT2 from Jatropha curcas and their functions in storage lipid biosynthesis

“…Further, studies have shown that the DGAT2s play a critical role in the accumulation of unusual FAs (such as epoxy and hydroxy fatty acids) in castor bean (Kroon et al 2006), tung tree (Shockey et al 2006) and Vernonia (Li et al 2010a). In addition, temporal and spatial expression patterns of DGAT1s and DGAT2s among organs or in different stages of seed development often display obvious differences (Li et al 2010b;Banilas et al 2011;Xu et al 2011). However, little is known about the functional similarity or divergence of DGAT1 and DGAT2 during the pathway of storage lipid biosynthesis in planta.…”