Background

Recently, in order to improve the resistance of flax plants to pathogen infection, transgenic flax that overproduces β-1,3-glucanase was created. β-1,3-glucanase is a PR protein that hydrolyses the β-glucans, which are a major component of the cell wall in many groups of fungi. For this study, we used fourth-generation field-cultivated plants of the Fusarium -resistant transgenic line B14 to evaluate how overexpression of the β-1,3-glucanase gene influences the quantity, quality and composition of flax fibres, which are the main product obtained from flax straw.

Results

Overproduction of β-1,3-glucanase did not affect the quantity of the fibre obtained from the flax straw and did not significantly alter the essential mechanical characteristics of the retted fibres. However, changes in the contents of the major components of the cell wall (cellulose, hemicellulose, pectin and lignin) were revealed. Overexpression of the β-1,3-glucanase gene resulted in higher cellulose, hemicellulose and pectin contents and a lower lignin content in the fibres. Increases in the uronic acid content in particular fractions (with the exception of the 1 M KOH-soluble fraction of hemicelluloses) and changes in the sugar composition of the cell wall were detected in the fibres of the transgenic flax when compared to the contents for the control plants. The callose content was lower in the fibres of the transgenic flax. Additionally, the analysis of phenolic compound contents in five fractions of the cell wall revealed important changes, which were reflected in the antioxidant potential of these fractions.

Conclusion

Overexpression of the β-1,3-glucanase gene has a significant influence on the biochemical composition of flax fibres. The constitutive overproduction of β-1,3-glucanase causes a decrease in the callose content, and the resulting excess glucose serves as a substrate for the production of other polysaccharides. The monosaccharide excess redirects the phenolic compounds to bind with polysaccharides instead of to partake in lignin synthesis. The mechanical properties of the transgenic fibres are strengthened by their improved biochemical composition, and the increased antioxidant potential of the fibres supports the potential use of transgenic flax fibres for biomedical applications.

Background

FlaxAid is a newly developed type of dressing enriched in particular flavonoids through genetic engineering of flax plants that exhibit health-promoting activities due to their strong antioxidant properties. The purpose of the current study was to assess the clinical efficacy of the FlaxAid bandage therapy for a patient affected with a diabetic foot ulcer which was unresponsive to previous treatments. The patient was treated with FlaxAid bandages for 12 weeks and the size and properties of the wound were routinely observed and recorded. Due to the the clinical picture of the wound study design was adopted whereby the comparative treatment was cotton gauze wetted with isotonic salt solution.

Findings

Following therapy, the foot ulcer decreased in size, despite the decompensation of advanced diabetes. It is believed that the beneficial nature of FlaxAid is derived from its high level and broad spectrum of antioxidants.

Conclusions

The FlaxAid dressing provides a novel and effective method for the treatment of diabetic foot ulcers. This study presents a preliminary pilot investigation and a larger number of subjects need to be included within the study in order to draw firm clinical conclusions. Efforts to this effect are currently under way.

Although arbuscular mycorrhizal fungi (AMF) are known for their positive effect on flax growth, the impact of genetic manipulation in this crop on arbuscular mycorrhiza and plant performance was assessed for the first time. Five types of transgenic flax that were generated to improve fiber quality and resistance to pathogens, through increased levels of either phenylpropanoids (W92.40), glycosyltransferase (GT4, GT5), or PR2 beta-1,3-glucanase (B14) or produce polyhydroxybutyrate (M50), were used. Introduced genetic modifications did not change the degree of mycorrhizal colonization as compared to parent cultivars Linola and Nike. Arbuscules were well developed in each tested transgenic type (except M50). In two lines (W92.40 and B14), a higher abundance of arbuscules was observed when compared to control, untransformed flax plants. However, in some cases (W92.40, GT4, GT5, and B14 Md), the mycorrhizal dependency for biomass production of transgenic plants was slightly lower when compared to the original cultivars. No significant influence of mycorrhiza on the photosynthetic activity of transformed lines was found, but in most cases P concentration in mycorrhizal plants remained higher than in nonmycorrhizal ones. The transformed flax lines meet the demands for better quality of fiber and higher resistance to pathogens, without significantly influencing the interaction with AMF.

Background

Flavonoids are a group of secondary plant metabolites important for plant growth and development. They show also a protective effect against colon and breast cancer, diabetes, hypercholesterolemic atherosclerosis, lupus nephritis, and immune and inflammatory reactions. Thus, overproduction of these compounds in flax by genetic engineering method might potentiate biotechnological application of these plant products.

Results

Flax plants of third generation overexpressing key genes of flavonoid pathway cultivated in field were used as plant material throughout this study. The biochemical properties of seed, oil and seedcake extracts and fibre from natural and transgenic flax plants were compared. The data obtained suggests that the introduced genes were stably inherited and expressed through plant generations.

Overproduction of flavonoid compounds resulted in increase of fatty acids accumulation in oil from transgenic seeds due to protection from oxidation offered during synthesis and seed maturation. The biochemical analysis of seedcake extracts from seeds of transgenic flax revealed significant increase in flavonoids (kaempferol), phenolic acids (coumaric, ferulic, synapic acids) and lignan content. Fibres, another product of flax plant showed increase in the level of catechine and acetylvanillone and decrease in phenolic acids upon flax modification.

Biochemical analysis results were confirmed using IR spectroscopy. The integral intensities of IR bands have been used for identification of the component of phenylpropanoid pathway in oil, seedcake extract and fibre from control and transgenic flax. It was shown that levels of flavonoids, phenolic acids and lignans in oil and seedcake extract was higher in transgenic flax products compared to control. An FT-IR study of fibres confirmed the biochemical data and revealed that the arrangement of the cellulose polymer in the transgenic fibres differs from the control; in particular a significant decrease in the number of hydrogen bonds was detected.

Conclusions

All analysed products from generated transgenic plants were enriched with antioxidant compounds derived from phenylopropanoid pathway Thus the products provide valuable source of flavonoids, phenolic acids and lignan for biomedical application. The compounds composition and quantity from transgenic plants was confirmed by IR spectroscopy. Thus the infrared spectroscopy appeared to be suitable method for characterization of flax products.

Background

In a previous study, anthocyanin levels in potato plants were increased by manipulating genes connected with the flavonoid biosynthesis pathway. However, starch content and tuber yield were dramatically reduced in the transgenic plants, which over-expressed dihydroflavonol reductase (DFR).

Results

Transgenic plants over-expressing dihydroflavonol reductase (DFR) were subsequently transformed with the cDNA coding for the glycosyltransferase (UGT) of Solanum sogarandinum in order to obtain plants with a high anthocyanin content without reducing tuber yield and quality. Based on enzyme studies, the recombinant UGT is a 7-O-glycosyltransferase whose natural substrates include both anthocyanidins and flavonols such as kaempferol and quercetin. In the super-transformed plants, tuber production was much higher than in the original transgenic plants bearing only the transgene coding for DFR, and was almost the same as in the control plants. The anthocyanin level was lower than in the initial plants, but still higher than in the control plants. Unexpectedly, the super-transformed plants also produced large amounts of kaempferol, chlorogenic acid, isochlorogenic acid, sinapic acid and proanthocyanins.

Conclusion

In plants over-expressing both the transgene for DFR and the transgene for UGT, the synthesis of phenolic acids was diverted away from the anthocyanin branch. This represents a novel approach to manipulating phenolic acids synthesis in plants.

Background

Even though the catecholamines (dopamine, norepinephrine and epinephrine) have been detected in plants their role is poorly documented. Correlations between norepinephrine, soluble sugars and starch concentration have been recently reported for potato plants over-expressing tyrosine decarboxylase, the enzyme mediating the first step of catecholamine synthesis. More recently norepinephrine level was shown to significantly increase after osmotic stress, abscisic acid treatment and wounding. Therefore, it is possible that catecholamines might play a role in plant stress responses by modulating primary carbon metabolism, possibly by a mechanism similar to that in animal cells. Since to date no catecholamine receptor has been identified in plants we transformed potato plants with a cDNA encoding human dopamine receptor (HD1).

Results

Tuber analysis of transgenic plants revealed changes in the activities of key enzymes mediating sucrose to starch conversion (ADP-glucose phosphorylase and sucrose synthase) and sucrose synthesis (sucrose phosphate synthase) leading to altered content of both soluble sugars and starch. Surprisingly the catecholamine level measured in transgenic plants was significantly increased; the reason for this is as yet unknown. However the presence of the receptor affected a broader range of enzyme activities than those affected by the massive accumulation of norepinephrine reported for plants over-expressing tyrosine decarboxylase. Therefore, it is suggested that the presence of the exogenous receptor activates catecholamine cAMP signalling in plants.

Conclusions

Our data support the possible involvement of catecholamines in regulating plant carbon metabolism via cAMP signalling pathway.