Fibres from flax overproducing β-1,3-glucanase show increased accumulation of pectin and phenolics and thus higher antioxidant capacity

Abstract

BackgroundRecently, 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.ResultsOverproduction 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.ConclusionOverexpression 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.

Biotechnology of fibrous flax in Europe and China

“…This is a tricky and time-consuming process; therefore not many studies have been reported on this subject. So far, some modifications were done to obtain better quality fiber in flax; moreover, first report on the properties and applications of the fiber from such modified plants have already been published (Preisner et al, 2014a;Skórkowska-Telichowska et al, 2011;Wojtasik et al, 2013;Wróbel-Kwiatkowska et al, 2007b).…”

“…The most commonly used method to introduce DNA fragments into plant genome is an Agrobacterium method, which is widely used also to improve fibrous plants productivity and quality (Day et al, 2009;Roach et al, 2011;Wahby et al, 2013;Wang et al, 2008;Wojtasik et al, 2013;Wróbel-Kwiatkowska et al, 2007a;Wróbel et al, 2004).…”

“…These researches are the first step to qualitative fiber improvements and some of the first attempts aiming to modify fiber composition are just being conducted. Flax plants overexpressing ˇ-1,3-glucanase, a PR protein, appeared to have fiber enriched in pectin and phenolics which strengthen the mechanical properties and antioxidant capacity of the fiber (Wojtasik et al, 2013).…”

Plant Fibre: Molecular Structure and Biomechanical Properties, of a Complex Living Material, Influencing Its Deconstruction towards a Biobased Composite

“…A target characteristic of the plant cell wall should be a high cellulose content and crystallinity, low level of lignification and cross linking [328]. Limiting lignin-hemicellulose-cellulose network linkages by modifying lignin content [329,330], pectin methylation [331], fucosyl substitution of xyloglucan [332,333], [Me]GlcA and acetylation substitution of xylan [334] or ferulic acid substitution of xylan [133] are other potential molecular targets for fibre modification. On the other hand, a high hemicellulose content is correlated with higher nanofibrillation of fibres and individualization of the microfibrils [335].…”

Transgenic flax/linseed (Linum usitatissimum L.) - expectations and reality

“…Identically, LorencKukula et al (2007) transformed flax with the aim of improving resistance to Fusarium. Wojtasik et al (2013) analysed the biochemical composition of GM flax fibres overexpressing the β-1,3-glucanase gene, they accentuated their improved mechanical properties and increased antioxidant potential supporting their biomedical applications. Chen et al (2008) focused on pyramiding of alleles with different rust resistance specificity in transgenic flax and creation of flax lines with multiple resistance characteristics.…”