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Transgenic Wheat (transgenic + wheat)

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Life Sciences	100%

Selected Abstracts

Transgenic wheat: where do we stand after the first 12 years?

ANNALS OF APPLIED BIOLOGY, Issue 1 2005
H.D. Shewry Jones
Abstract Wheat was among the last of the major crops to be transformed (in 1992), and transformation is still difficult, with a lower efficiency than that for maize and rice. However, the recent development of Agrobacterium -based systems is set to improve the precision of the process, while new methods of selection, removal of unnecessary DNA sequences, gene targeting and in vivo mutagenesis will make the process cleaner and more acceptable to regulatory authorities and consumers. Our current work is focussed on using transformation to understand and manipulate aspects of grain processing quality, notably dough strength and texture for milling. However, it is clear that a major priority for future work will be to improve nutritional quality, including vitamin and mineral contents for the developing world and starch digestibility and dietary fibre content and composition for developed countries. [source]

Enhancing lignan biosynthesis by over-expressing pinoresinol lariciresinol reductase in transgenic wheat

MOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 12 2007
Allan K. Ayella
Abstract Lignans are phenylpropane dimers that are biosynthesized via the phenylpropanoid pathway, in which pinoresinol lariciresinol reductase (PLR) catalyzes the last steps of lignan production. Our previous studies demonstrated that the contents of lignans in various wheat cultivars were significantly associated with anti-tumor activities in APCMin mice. To enhance lignan biosynthesis, this study was conducted to transform wheat cultivars (,Bobwhite', ,Madison', and ,Fielder', respectively) with the Forsythia intermedia PLR gene under the regulatory control of maize ubiquitin promoter. Of 24 putative transgenic wheat lines, we successfully obtained 3 transformants with the inserted ubiquitin-PLR gene as screened by PCR. Southern blot analysis further demonstrated that different copies of the PLR gene up to 5 were carried out in their genomes. Furthermore, a real-time PCR indicated ,17% increase of PLR gene expression over the control in 2 of the 3 positive transformants at T0 generation. The levels of secoisolariciresinol diglucoside, a prominent lignan in wheat as determined by HPLC-MS, were found to be 2.2-times higher in one of the three positive transgenic sub-lines at T2 than that in the wild-type (117.9 ± 4.5 vs. 52.9 ± 19.8 ,g/g, p <0.005). To the best of our knowledge, this is the first study that elevated lignan levels in a transgenic wheat line has been successfully achieved through genetic engineering of over-expressed PLR gene. Although future studies are needed for a stably expression and more efficient transformants, the new wheat line with significantly higher SDG contents obtained from this study may have potential application in providing additive health benefits for cancer prevention. [source]

Generation of transgenic wheat (Triticum aestivum L.) accumulating heterologous endo-xylanase or ferulic acid esterase in the endosperm

PLANT BIOTECHNOLOGY JOURNAL, Issue 3 2010
Jesper Harholt
Summary Endo-xylanase (from Bacillus subtilis) or ferulic acid esterase (from Aspergillus niger) were expressed in wheat under the control of the endosperm-specific 1DX5 glutenin promoter. Constructs both with and without the endoplasmic reticulum retention signal (Lys-Asp-Glu-Leu) KDEL were used. Transgenic plants were recovered in all four cases but no qualitative differences could be observed whether KDEL was added or not. Endo-xylanase activity in transgenic grains was increased between two and threefold relative to wild type. The grains were shrivelled and had a 25%,33% decrease in mass. Extensive analysis of the cell walls showed a 10%,15% increase in arabinose to xylose ratio, a 50% increase in the proportion of water-extractable arabinoxylan, and a shift in the MW of the water-extractable arabinoxylan from being mainly larger than 85 kD to being between 2 and 85 kD. Ferulic acid esterase-expressing grains were also shrivelled, and the seed weight was decreased by 20%,50%. No ferulic acid esterase activity could be detected in wild-type grains whereas ferulic acid esterase activity was detected in transgenic lines. The grain cell walls had 15%,40% increase in water-unextractable arabinoxylan and a decrease in monomeric ferulic acid between 13% and 34%. In all the plants, the observed changes are consistent with a plant response that serves to minimize the effect of the heterologously expressed enzymes by increasing arabinoxylan biosynthesis and cross-linking. [source]

A metabolomic study of substantial equivalence of field-grown genetically modified wheat

PLANT BIOTECHNOLOGY JOURNAL, Issue 4 2006
John M. Baker
Summary The ,substantial equivalence' of three transgenic wheats expressing additional high-molecular-weight subunit genes and the corresponding parental lines (two lines plus a null transformant) was examined using metabolite profiling of samples grown in replicate field trials on two UK sites (Rothamsted, Hertfordshire and Long Ashton, near Bristol) for 3 years. Multivariate comparison of the proton nuclear magnetic resonance spectra of polar metabolites extracted with deuterated methanol,water showed a stronger influence of site and year than of genotype. Nevertheless, some separation between the transgenic and parental lines was observed, notably between the transgenic line B73-6-1 (which had the highest level of transgene expression) and its parental line L88-6. Comparison of the spectra showed that this separation resulted from increased levels of maltose and/or sucrose in this transgenic line, and that differences in free amino acids were also apparent. More detailed studies of the amino acid composition of material grown in 2000 were carried out using gas chromatography-mass spectrometry. The most noticeable difference was that the samples grown at Rothamsted consistently contained larger amounts of acidic amino acids (glutamic, aspartic) and their amides (glutamine, asparagine). In addition, the related lines, L88-6 and B73-6-1, both contained larger amounts of proline and ,-aminobutyric acid when grown at Long Ashton than at Rothamsted. The results clearly demonstrate that the environment affects the metabolome and that any differences between the control and transgenic lines are generally within the same range as the differences observed between the control lines grown on different sites and in different years. [source]