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Diversity of ?12 fatty acid desaturases in santalaceae and their role in production of seed oil acetylenic fatty acids.

ABSTRACT: Plants in the Santalaceae family, including the native cherry Exocarpos cupressiformis and sweet quandong Santalum acuminatum, accumulate ximenynic acid (trans-11-octadecen-9-ynoic acid) in their seed oil and conjugated polyacetylenic fatty acids in root tissue. Twelve full-length genes coding for microsomal ?12 fatty acid desaturases (FADs) from the two Santalaceae species were identified by degenerate PCR. Phylogenetic analysis of the predicted amino acid sequences placed five Santalaceae FADs with ?12 FADs, which include Arabidopsis thaliana FAD2. When expressed in yeast, the major activity of these genes was ?12 desaturation of oleic acid, but unusual activities were also observed: i.e. ?15 desaturation of linoleic acid as well as trans-?12 and trans-?11 desaturations of stearolic acid (9-octadecynoic acid). The trans-12-octadecen-9-ynoic acid product was also detected in quandong seed oil. The two other FAD groups (FADX and FADY) were present in both species; in a phylogenetic tree of microsomal FAD enzymes, FADX and FADY formed a unique clade, suggesting that are highly divergent. The FADX group enzymes had no detectable ?12 FAD activity but instead catalyzed cis-?13 desaturation of stearolic acid when expressed in yeast. No products were detected for the FADY group when expressed recombinantly. Quantitative PCR analysis showed that the FADY genes were expressed in leaf rather than developing seed of the native cherry. FADs with promiscuous and unique activities have been identified in Santalaceae and explain the origin of some of the unusual lipids found in this plant family.

SUBMITTER: Okada S

PROVIDER: S-EPMC3820875 | biostudies-literature | 2013 Nov

REPOSITORIES: biostudies-literature

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Diversity of Δ12 fatty acid desaturases in santalaceae and their role in production of seed oil acetylenic fatty acids.

Okada Shoko S Zhou Xue-Rong XR Damcevski Katherine K Gibb Nerida N Wood Craig C Hamberg Mats M Haritos Victoria S VS

The Journal of biological chemistry 20130923 45

Plants in the Santalaceae family, including the native cherry Exocarpos cupressiformis and sweet quandong Santalum acuminatum, accumulate ximenynic acid (trans-11-octadecen-9-ynoic acid) in their seed oil and conjugated polyacetylenic fatty acids in root tissue. Twelve full-length genes coding for microsomal Δ12 fatty acid desaturases (FADs) from the two Santalaceae species were identified by degenerate PCR. Phylogenetic analysis of the predicted amino acid sequences placed five Santalaceae FADs ...[more]

PMID: 24062307

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Project description:Condensed tannins (CT), one of the most ubiquitous compounds in the plant kingdom, can modulate ruminal nutrient metabolism. Objectives were to study potential interactions of CT and polyunsaturated fatty acids (PUFA) on ruminal fermentation, biohydrogenation (BH), and methane production. Ruminal fluid obtained from lactating Holstein Friesian cows was used. All experiments were carried out as a completely randomized design with the same mixed diet: control (60:40 forage:concentrate) without supplement (CON), 2.5% soybean oil (SBO), and SBO + grape seed tannin extract (GSTE) at 0.2%, 0.4%, 0.6%, or 0.8% dietary DM (ST0.2, ST0.4, ST0.6, and ST0.8, respectively). Compared with CON (84.7 mM), total VFA concentration was not affected by SBO, but decreased (P < 0.001) with ST0.8 vs. ST0.6 (75.3 vs. 78.3 mM). Relative to CON, methane production was depressed (P < 0.001) by 17.7% and 28.0% in ST0.4 and ST0.8. The highest (P < 0.001) mean concentrations of c9,t11 CLA and C18:1 t11 were observed with ST0.4 compared with CON, but there was no difference between SBO and CT-containing diets. Disappearance of C18:2 c9,c12 was 49.1% vs. 50.3% in CON vs. SBO, whereas it ranged from 39.9% to 46.3% in CT-containing diets after 2 h incubation (P < 0.001). Concentrations of c9,t11 CLA with supplemental SBO and ST0.8 nearly peaked (P < 0.001) at 2 h incubation, but this fatty acid peaked (P > 0.05) at 6 h incubation and remained higher (P < 0.001; 15.9-17.0 µg/mL) at 24 h incubation with ST0.2, ST0.4, and ST0.6 compared with other diets (13.5-14.5 µg/mL). Compared with CON (50.6 µg/mL), concentration of C18:1 t11 with SBO and CT-containing diets reached a peak (P < 0.001; 241-265 µg/mL) at 12 h incubation. Concentration of C18:0 was 171%-231% higher (P < 0.001) with SBO and CT relative to CON at 24 h incubation. Overall, these results demonstrated that PUFA in SBO are more effective in modulating ruminal BH and CH4 production when combined with CT. However, high doses of added CT can reduce ruminal VFA concentration. Thus, a level of 0.4% GSTE added to diets containing 2.5% PUFA from plant origin might be suitable for optimizing ruminal fermentation and BH of C18:2 c9,c12 to fatty acid intermediates that could have beneficial effects to human health.

Dataset Information

Diversity of ?12 fatty acid desaturases in santalaceae and their role in production of seed oil acetylenic fatty acids.

Publications

Diversity of Δ12 fatty acid desaturases in santalaceae and their role in production of seed oil acetylenic fatty acids.

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