My Plant Science Overview |
Written by Tam Nguyen |
Saturday, 06 September 2008 05:00 |
1. Boost astaxanthin and EPA in soybean and camelina seeds
Camelina seeds look dark orange (top right and circle-bottom) compare with wild type seed (top left or center-bottom)
2. Redirection of Metabolic Flux for High Levels of Omega-7 Monounsaturated Fatty Acid Accumulation in Camelina seed Seed oils enriched in omega-7 monounsaturated fatty acids, including palmitoleic acid (16:1D9) and cis-vaccenic acid (18:1D11), 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 delta 9 desaturation of stearoyl (18:0)-acyl carrier protein (ACP) to delta 9 desaturation of palmitoyl (16:0)-acyl carrier protein (ACP) and –coenzyme A (CoA). This was achieved by seed-specific co-expression of a mutant delta 9-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 monounsaturated fatty acid accumulation to ~ 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 delta 9-acyl-ACP desaturase and by blocking C18 fatty acid elongation. Seeds from these lines also had total saturated fatty acids reduced to ~5% of the seed oil versus ~12% in seeds of non-transformed plants. Consistent with accumulation of triacylglycerol species with shorter fatty acid chain-lengths and increased monounsaturation, seed oils from engineered lines had marked shifts in thermotropic properties that may be of value for biofuel applications. 3. Camelina Seed Transcriptome: A Tool for Meal and Oil Improvement and Translational Research Camelina (Camelina sativa), a Brassicaceae oilseed, has received intense interest as a biofuel crop and production platform for industrial oils. Limiting wider production of camelina for these uses is the need to improve the quality and content of the seed protein rich-meal and oil, which is enriched in oxidatively unstable polyunsaturated fatty acids that are deleterious for biodiesel. To identify candidate genes for meal and oil quality improvement, we built a transcriptome reference from 2,047 Sanger ESTs and over 2 million 454-derived sequence reads, representing genes expressed in developing camelina seeds. The transcriptome of ~60K transcripts from 22,597 putative genes includes camelina homologs of nearly all known seed-expressed genes, suggesting a high level of completeness and usefulness of the reference. These sequences included candidates for 12S (cruciferins) and 2S (napins) seed storage proteins (SSPs) and nearly all known lipid genes, which have been compiled into an accessible database. To demonstrate the utility of the transcriptome for seed quality modification, seed-specific RNAi lines deficient in napins were generated by targeting 2S SSP genes, and high oleic acid oil lines were obtained by targeting fatty acid desaturase 2 (FAD2) and fatty acid elongase 1 (FAE1). The high sequence identity between Arabidopsis and camelina genes was also exploited to engineer high oleic lines by RNAi with Arabidopsis FAD2 and FAE1 sequences. It is expected that this transcriptomic data will be useful for breeding and engineering of additional camelina seed traits and for translating findings from the model Arabidopsis thaliana to an oilseed crop. 4. Omega7, turn nothing into 70% The essential unsaturated omega-7 fatty acid which include palmitoleic acid and cis-vaccenic acid are of particular importance, because it confers fluidity to the membrane, whilst having a low susceptibility to oxidation. Lipid peroxidation by free radicals results in the disintegration of membranes and a resultant loss of function, leading to ulceration of the digestive tract, a disturbed epidermal barrier in the skin, and dryness of the genital tract lining. Omega-7, together with the other classes of omega-7 play an important role in regulating immune function and the inflammatory response. Thus omega-7 fatty acids promote tissue regeneration and anti-inflammatory action in the skin and mucosa. http://www.plantphysiol.org/content/154/4/1897.full.pdf
Gas chromatograph-mass spectrometer (GCMS) analysis fatty acid single seed of control (top) and transgenic (bottom) seeds 5. Engineering Plant Oils
While conversion of an unsaturated oil to an oil with increased saturated fatty acid levels may not sound like a boon to those conscious about consuming unsaturated fats, the development of new plant seed oils has several potential biotechnological Scientists have known for a long time that the ratio of saturated to unsaturated fatty acids plays a key role in plants’ ability to adapt to different climates, but to change this ratio specifically in seed oils without changing the climate is an interesting challenge, we sought to gain a better understanding of the enzymes and metabolic pathways that produce these oils to find ways to manipulate the accumulation of fats using genetic techniques.
Gas chromatograph-mass spectrometer (GCMS) analysis fatty acid single seed of KasII-Hairpin Antisense seed Suppression of kasII enzyme activity by KasII Hairpin Antisense due to reducing 18:0, 18:1 (delta 9), 18:2 and 18:3 fatty acid (diagram at very top) and result analysis fatty acid by GCMS of transgenic (bottom) and control (top) seeds showed that an accumulation of 16:0 Fatty acid due to enhance 16:1 delta 9 and 18:1 delta11 fatty acids (Source: unpublished) We performed experiments on Arabidopsis, a plant commonly used in research. Like other plants from temperate climates (e.g., canola, soybean, and sunflower), Arabidopsis contains predominantly 18-carbon unsaturated fatty acids in its seed oil.
For example, such a technique could lead to the engineering of temperate crop plants to produce seeds containing saturated oils that can be further modified to produce renewable feedstocks for industrial processes. Such renewable resources could help reduced dependence on petroleum. Conversely, methods to increase the activity of KASII, and therefore the production of 18-carbon desaturated plant oils, may provide a useful strategy to limit the accumulation of saturated fatty acids in edible oils, leading to more healthful nutrition.
Cross section of stems show that a high GUS gene expression at T7RNAP system (left) than a regular system (right) We are reporting the development of a new powerful tool for plant expression system based on the T7 RNA polymerase that may have major impact on plant biotechnology and on functional genomic studies as well. Our results not only demonstrate the use of T7 system for simple overexpression of foreign gene in higher plants but also in a highly tissue specific manner. Also, in these studies we demonstrate that the T7 system can be used to regulate the expression of foreign gene through inducible mechanisms, akin to inducible expression of recombinant proteins E. coli based on T7
In addition, I designed a lot of binary vectors for plant transformation, used a lot of genes such as KasII, Fad2, Fad3, FatB, Com25, T7RNAP, GusA, Ds-Red, Zs-green, Zs-yellow, GFP, Ferritin, Vitamin A, GluB1, HBsAg etc. Beside above technology, many promoters such as Phaseolin, 35S CaMV, rbcS-3A, kin1, cor6.6, gluB1, P170, T7 etc have been used for expression at different plant tissues specific in different purposes. And I have expert at almost molecular biology techniques.
www.omega-7.org |
Last Updated on Friday, 16 May 2014 16:43 |