Biochemical pathways in seed oil synthesis

Bates, Philip D.; Stymne, Sten; Ohlrogge, John B.

doi:10.1016/j.pbi.2013.02.015

Cited by 433 publications

(478 citation statements)

References 74 publications

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“…Both polyols (mannitol) and oligosaccharides (raffinose and stachyose) are synthesized in olive tree leaves, being further exported with sucrose into the fruits, for both general metabolism and as precursors of olive oil biosynthesis (8). Starting from a carbon source such as sucrose, long-chain fatty acids are synthesized, modified and degraded by the activity of enzymes, including fatty-acid synthases, elongases, desaturases and carboxylases (9). Fatty acids are the major constituent of triacylglycerols (TAG).…”

Section: /Bodymentioning

confidence: 99%

Genome of wild olive and the evolution of oil biosynthesis

Ünver

Wu²,

Sterck

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

235

265

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SignificanceWe sequenced the genome and transcriptomes of the wild olive (oleaster). More than 50,000 genes were predicted, and evidence was found for two relatively recent whole-genome duplication events, dated at about 28 and 59 million years ago. Whole genome sequencing, as well as gene expression studies, provide further insights into the evolution of oil biosynthesis, and will aid future studies aimed at further increasing the production of olive oil, which is a key ingredient of the healthy Mediterranean diet and has been granted a qualified health claim by FDA. 5 AbstractHere, we present the genome sequence and annotation of the wild olive tree (Olea europaea var. sylvestris), called oleaster, which is considered an ancestor of cultivated olive trees. More than 50,000 protein-coding genes were predicted, a majority of which could be anchored to 23 pseudo-chromosomes obtained through a newly constructed genetic map. The oleaster genome contains signatures of two Oleaceae-lineage specific paleopolyploidy events, dated at approximately 28 and 59 million years ago. These events contributed to the expansion and neofunctionalization of genes and gene families that play important roles in oil biosynthesis.The functional divergence of oil biosynthesis pathway genes, such as FAD2, SACPD, EAR and ACPTE, following duplication, has been responsible for the differential accumulation of oleic and linoleic acids produced in olive compared to sesame, a closely related oil crop. Duplicated oleaster FAD2 genes are regulated by a short-interfering RNA (siRNA) derived from a transposable element-rich region, leading to suppressed levels of FAD2 gene expression.Additionally, neofunctionalization of members of the SACPD gene family has led to increased expression of SACPD2, 3, 5 and 7, consequently resulting in an increased desaturation of steric acid. Taken together, decreased FAD2 expression and increased SACPD expression likely explain the accumulation of exceptionally high levels of oleic acid in olive. The oleaster genome thus provides important insights into the evolution of oil biosynthesis and will be a valuable resource for oil crop genomics. 6 /bodyAs a symbol of peace, fertility, health and longevity, the olive tree (Olea europaea L.) is a socio-economically important oil crop that is widely grown in the Mediterranean Basin.Belonging to the Oleaceae family (order Lamiales), it can biosynthesize essential unsaturated fatty acids and other important secondary metabolites, such as vitamins and phenolic compounds (1). The olive tree is a diploid (2n = 46) allogamous crop that can be vegetatively propagated and live for thousands of years (2). Paleobotanical evidence suggests that olive oil was already produced in the Bronze Age (3). It has been thought that cultivated varieties were derived from the wild olive tree, called oleaster (O. europaea var. sylvestris), in Asia Minor, which then spread to Greece (4). Nevertheless, the exact domestication history of the olive tree is unknown (5). Due to their longevity, oleaster...

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Section: /Bodymentioning

confidence: 99%

Genome of wild olive and the evolution of oil biosynthesis

Ünver

Wu²,

Sterck

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

235

265

View full text Add to dashboard Cite

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“…Subsequently, a second FA is attached to the sn2 position, followed by various additions to the phosphate group [ 2 1 1 _ T D $ D I F F ] (or even its replacement) at the sn3 position, which will give rise to the polar head group [44,45]. Interestingly, mycorrhizal cells induce a specific GPAT referred to as REQUIRED FOR ARBUSCULAR MYCORRHIZA2 (RAM2) owing to its AM-defective mutant phenotype [46].…”

Section: Non-membrane Lipid Functions?mentioning

confidence: 99%

Diet of Arbuscular Mycorrhizal Fungi: Bread and Butter?

Rich

Nouri

Courty

et al. 2017

Trends in Plant Science

155

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Most plants entertain mutualistic interactions known as arbuscular mycorrhiza (AM) with soil fungi (Glomeromycota) which provide them with mineral nutrients in exchange for reduced carbon from the plant. Mycorrhizal roots represent strong carbon sinks in which hexoses are transferred from the plant host to the fungus. However, most of the carbon in AM fungi is stored in the form of lipids. The absence of the type I fatty acid synthase (FAS-I) complex from the AM fungal model species Rhizophagus irregularis suggests that lipids may also have a role in nutrition of the fungal partner. This hypothesis is supported by the concerted induction of host genes involved in lipid metabolism. We explore the possible roles of lipids in the light of recent literature on AM symbiosis. Carbohydrates in AM Fungal NutritionAM fungi are strictly biotrophic, in other words they depend on their host to complete their life cycle. Although the basis of biotrophy is poorly understood, it has been suggested that it is due to the dependency of AM fungi on some essential nutritional factor(s) from the host [1]. Direct uptake measurements revealed that intraradical mycelium (IRM) can take up carbohydrates, whereas extraradical mycelium (ERM) did not acquire significant amounts of carbohydrates [2,3]. Perhaps this is because AM fungal genes involved in nutrient uptake are expressed only in the host, which would explain their biotrophy. Tracer studies on mycorrhizal roots, and respirometric analysis on isolated intraradical hyphae have established glucose as a central substrate for AM fungi [3][4][5], and indeed a monosaccharide transporter has been identified in the fungal partner [6]. Mycorrhizal roots represent strong carbon sinks [2,4,7], suggesting that they attract sucrose from photosynthetic source tissues. Sucrose is thought to be cleaved in the vicinity of the fungus by invertases and sucrose synthase [8], resulting in monosaccharides (glucose and fructose) that are released to the fungus and taken up by its IRM [5,6]. However, in the fungal storage compartments -the spores and the vesicles -carbon is stored primarily in the form of lipids, with minor amounts of the glucose polymer glycogen. We discuss here salient issues relating to carbohydrate and lipid metabolism in AM fungi and their significance for fungal nutrition during symbiosis. Lipid Metabolism in AM Fungi -Open Questions and SurprisesAlthough the aforementioned carbon fluxes in AM fungi have been firmly established, several questions remain open. AM fungi store and transport most of their carbon in the form of lipids [9][10][11][12]. However, AM fungi cannot produce the basic fatty acid (FA) palmitate (C16) in the absence of their host (as shown in two distantly related species, Rhizophagus irregularis and Gigaspora rosea), while FA elongation and desaturation can occur independently of the plant [13]. This and similar results suggested that AM fungi can only synthesize C16 in the IRM [3,13]. Taken together, the available evidence suggests that AM fungi take up sugars (...

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“…Furthermore, EYFP-G3Pp4 localized in the plastids (Figure 2 and Supplemental Figure S2). All these results indicate that G3Pp4 is a plastid-localized G3P transporter, expressed during late embryogenesis and supply G3P to the cytosol to be used for storage lipid synthesis in the endoplasmic reticulum (ER) (Bates et al 2013).…”

Section: Discussionmentioning

confidence: 97%

Arabidopsis glycerol-3-phosphate permease 4 is localized in the plastids and involved in the accumulation of seed oil

Kawai

Ishikawa

Mitsui

et al. 2014

Plant Biotechnology

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In plant cells, glycerol 3-phosphate (G3P) is apparently able to permeate the plastid envelope, but no specific transporter has been characterized so far. The Arabidopsis five G3Pp proteins have been predicted as putative G3P permeases because of their high homologies with the prokaryotic G3P/phosphate antiporter GlpT. In the present study, G3Pp4 was characterized in detail utilizing reverse genetic approaches. Promoter analysis using GUS expression revealed that G3Pp4 was expressed strongly throughout the embryos during late developmental stages, and the seed lipid contents decreased in two g3pp4 knockout mutants. An enhanced yellow fluorescent protein-fused G3Pp4 was localized in the plastids, functioned physiologically in A. thaliana, and had G3P-transport activity in E. coli. These results suggest that Arabidopsis G3Pp4 is a plastid envelope-localized G3P transporter and involved in accumulation of storage lipids in late embryogenesis.

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Biochemical pathways in seed oil synthesis

Cited by 433 publications

References 74 publications

Genome of wild olive and the evolution of oil biosynthesis

Genome of wild olive and the evolution of oil biosynthesis

Diet of Arbuscular Mycorrhizal Fungi: Bread and Butter?

Arabidopsis glycerol-3-phosphate permease 4 is localized in the plastids and involved in the accumulation of seed oil

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