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Genome Assembly Of The Brassicaceae Diploid Orychophragmus Violaceus Reveals Complex Whole-Genome Duplication And Evolution Of Dihydroxy Fatty Acid Metabolism, Fan Huang, Peng Chen, Xinyu Tang, Ting Zhong, Taihua Yang, Chinedu Charles Nwafor, Chao Yang, Xianhong Ge, Hong An, Zaiyun Li, Edgar B. Cahoon, Chunyu Zhang

Center for Plant Science Innovation: Faculty and Staff Publications

Orychophragmus violaceus is a Brassicaceae species widely cultivated in China, particularly as a winter cover crop in northern China because of its low-temperature tolerance and low water demand. Recently, O. violaceus has also been cultivated as a potential industrial oilseed crop because of its abundant 24- carbon dihydroxy fatty acids (diOH-FAs), which contribute to superior high-temperature lubricant properties. In this study, we performed de novo assembly of the O. violaceus genome. Whole-genome synteny analysis of the genomes of its relatives demonstrated that O. violaceus is a diploid that has undergone an extra whole-genome duplication (WGD) after the Brassicaceae-specific α-WGD event, …

Molecular-Assisted Breeding For Soybean With High Oleic/Low Linolenic Acid And Elevated Vitamin E In The Seed Oil, Katherine Hagely, Anji Reddy Konda, Jeong-Hwa Kim, Edgar B. Cahoon, Kristin Bilyeu

Center for Plant Science Innovation: Faculty and Staff Publications

The uses of vegetable oils are determined by functional properties arising from their chemical composition. Soybean oil was previously used in margarines and baked foods after partial hydrogenation to achieve heat and oxidative stability. This process, however, generates trans fats that are now excluded from food use because of cardiovascular health risks. Also present in soybean oil are the anti-oxidant tocopherols, with α- tocopherol (vitamin E) typically present as a minor component compared to γ-tocopherol. Genetic improvement of the fatty acid profile and tocopherol profile is an attractive solution to increase the functional and health qualities of soybean oil. The …

Redirection Of Metabolic Flux For High Levels Of Omega-7 Monounsaturated Fatty Acid Accumulation In Camelina Seeds, Huu Tam Nguyen, Hyunwoo Park, Karen L. Koster, Rebecca E. Cahoon, Hanh Nguyen, John Shanklin, Thomas E. Clemente, Edgar B. Cahoon

Center for Plant Science Innovation: Faculty and Staff Publications

Seed oils enriched in omega-7 monounsaturated fatty acids, including palmitoleic acid (16:1Δ9) and cis-vaccenic acid (18:1Δ11), have nutraceutical and industrial value for polyethylene production and biofuels. Existing oilseed crops accumulate only small amounts (<2%) of these novel fatty acids in their seed oils. We demonstrate a strategy for enhanced production of omega-7 monounsaturated fatty acids in camelina (Camelina sativa) and soybean (Glycine max) that is dependent on redirection of metabolic flux from the typical Δ9 desaturation of stearoyl (18:0)-acyl carrier protein (ACP) to Δ9 desaturation of palmitoyl (16:0)-acyl carrier protein (ACP) and coenzyme A (CoA). This was achieved by seed-specific co-expression of a mutant Δ9-acyl-ACP and an acyl-CoA desaturase with high specificity for 16:0-ACP and CoA substrates, respectively. This strategy was most effective in camelina where seed oils with ~17% omega-7 monounsaturated fatty acids were obtained.

Further increases in omega-7 fatty acid accumulation to 60–65% of the total fatty acids in camelina seeds were achieved by inclusion of seed-specific suppression of 3-keto-acyl-ACP synthase II and the FatB 16:0-ACP thioesterase genes to increase substrate pool sizes of 16:0-ACP for the Δ9-acyl-ACP desaturase and by blocking C18 fatty acid elongation. Seeds from these lines also had total saturated fatty acids reduced to ~5% of …

A Thraustochytrid Diacylglycerol Acyltransferase 2 With Broad Substrate Specificity Strongly Increases Oleic Acid Content In Engineered Arabidopsis Thaliana Seeds, Chunyu Zhang, Umidjon Iskandarov, Elliott T. Klotz, Robyn L. Stevens, Rebecca E. Cahoon, Tara J. Nazarenus, Suzette L. Pereira, Edgar B. Cahoon

Center for Plant Science Innovation: Faculty and Staff Publications

Diacylglycerol acyltransferase (DGAT) catalyses the last step in acyl-CoA-dependent triacylglycerol (TAG) biosynthesis and is an important determinant of cellular oil content and quality. In this study, a gene, designated TaDGAT2, encoding a type 2 DGAT (DGAT2)-related enzyme was identified from the oleaginous marine protist Thraustochytrium aureum. The deduced TaDGAT2 sequence contains a ~460 amino acid domain most closely related to DGAT2s from Dictyostelium sp. (45–50% identity). Recombinant TaDGAT2 restored TAG biosynthesis to the Saccharomyces cerevisiae H1246 TAG-deficient mutant, and microsomes from the complemented mutant displayed DGAT activity with C16 and C18 saturated and unsaturated fatty acyl-CoA and diacylglycerol …