Flax (Linum usitatissimum L.) peroxidase cDNAs (FLXPER1--4) were isolated from a lambdagt10 shoot library using probes encoding the amino termini of class III plant peroxidases. These probes were obtained by PCR amplification of the library with lambda primers flanking the EcoRI cloning site, and a mixed oligonucleotide corresponding to the catalytic domain (HFHDCFV) found in secretory plant peroxidases. The transcriptional expressions of FLXPER1 and FLXPER2 appear to be specific to stem based on northern blot analyses. FLXPER1 and FLXPER2 encode acidic peroxidases of calculated isoelectric points (pIc) 4.6 and 4.7, respectively. However, FLXPER1 differs from FLXPER2 in amino acid sequence and in the possession of additional amino acids at its carboxy terminus containing motifs found in membrane-anchored proteins. The FLXPER1 anchoring motifs show striking similarity to those found in a blue copper-type protein (LP18) whose expression in pea (Pisum sativum) has been correlated with lignin deposition. FLXPER3 is expressed in leaf, root, and stein. Partial genomic sequences of FLXPER3 and a highly homologous FLXPER5 were also obtained. FLXPER3 and FLXPER5 do not have the typical class HI plant peroxidase third intron, located within the highly conserved VALSGAHT haem-binding motif. FLXPER3 and FLXPER5 do have, however, an intron downstream of this motif at a location not found in any other class III plant peroxidase gene. FLXPER4 encodes a basic (pIc 8.5) extracellular peroxidase. A modified version of the restriction fragment length polymorphism-coupled domain-directed differential display (RC4D) technique was used to evaluate class III peroxidase transcriptional expression in flax organs. The method revealed the expression of 20 to 30 peroxidase genes in each plant organ examined. It also confirmed the stem-specific nature of FLXPER2 and the ubiquitous character of FLXPER3. FLXPER1 was found in all organs investigated in contrast to results observed by northern b

Thesis (Ph. D.)--Dept of Agronomy, University of Adelaide, 1987. / Includes bibliographical references (136-146).

Thesis, Basel.

Due to a rising interest in natural fibres for textiles as well as environmental concerns, the demand for fibre flax has increased in recent decades. It was, therefore, with great enthusiasm that Canadian farmers welcomed, in 1997, the opening of a flaxprocessing unit in the region of Salaberry-de-Valleyfield, Quebec. The purpose of this study was to investigate the economic viability of fibre flax contracting as an alternative activity for field-crop producers in Quebec. A risk-programming model called minimization of total absolute deviation (MOTAD) was developed to better approach this issue. The MOTAD takes into account the variability in income that stems from uncertainty in commodity-market prices and yields. In addition, five different marketing strategies for pricing grain corn and soybeans were included in the model. These pricing techniques combined the use of futures and options markets. / In a global agricultural system, where international commitments force governments to cut subsidies, reducing income variability for risk-averse farmers becomes a critical challenge. This study offered to assess the contribution of both contracting and futures markets as alternative market instruments for risk management. Five portfolio farm plans were identified for 200- and 300-hectare farm sizes. The results showed that gains through fibre flax contracting, in terms of risk reduction, exist only for the farm plans with lower levels of income and risk. Moreover, simulations demonstrated that the use of futures and options markets can help maximize overall net farm return.

No description available.

No description available.

Flax fibers can be used as environmentally friendly alternatives to conventional reinforcing fibers (e.g., glass) in composites. The interest in natural fiber-reinforced polymer composites is growing rapidly due to its high performance in terms of mechanical properties, significant processing advantages, excellent chemical resistance, low cost and low density. These advantages place natural fiber composites among the high performance composites having economic and environmental advantages. In the field of technical utilization of plant fibers, flax fiber-reinforced composites represent one of the most important areas. On the other hand, lack of good interfacial adhesion and poor resistance to moisture absorption make the use of natural fiber-reinforced composites less attractive. In order to improve their interfacial properties, fibers were subjected to chemical treatments, namely, mercerization, silane treatment, benzoylation, and peroxide treatment. Selective removal of non-cellulosic compounds constitutes the main objective of the chemical treatments of flax fibers to improve the performance of fiber-reinforced composites. The objective of this study was to determine the effects of pre-treated flax fibers on the performance of the fiber-reinforced composites. Short flax fibers were derived from Saskatchewan-grown flax straws, for use in fiber-reinforced composites. Composites consisting of high-density polyethylene (HDPE) or linear low-density polyethylene (LLDPE) or HDPE/LLDPE mix, chemically treated fibers and additives were prepared by the extrusion process. Extrusion is expected to improve the interfacial adhesion significantly as opposed to simple mixing of the two components. The extruded strands were then pelletized and ground. The test samples were prepared by rotational molding. The fiber surface topology and the tensile fracture surfaces of the composites were characterized by scanning electron microscopy to determine whether the modified fiber-matrix interface had improved interfacial bonding. Mechanical and physical properties of the composites were evaluated. The differential scanning calorimetry technique was also used to measure the melting point of flax fiber and composite. Overall, the scanning electron microscopy photographs of fiber surface characteristics and fracture surfaces of composites clearly indicated the extent of fiber-matrix interface adhesion. Chemically treated fiber-reinforced composites showed better fiber-matrix interaction as observed from the good dispersion of fibers in the matrix system. Compared to untreated fiber-reinforced composites, all the treated fiber-reinforced composites had the same tendency to slightly increase the tensile strength at yield of composites. Silane, benzoylation, and peroxide treated fiber-reinforced composites offered superior physical and mechanical properties. Strong intermolecular fiber-matrix bonding decreased the high rate of water absorption in biocomposites. The incorporation of 10% untreated or chemically treated flax fibers also increased the melting point of composites. Further investigation is required to address the effect of increase in fiber content on the performance of composites.

Flax fibers can be used as environmentally friendly alternatives to conventional reinforcing fibers (e.g., glass) in composites. The interest in natural fiber-reinforced polymer composites is growing rapidly due to its high performance in terms of mechanical properties, significant processing advantages, excellent chemical resistance, low cost and low density. These advantages place natural fiber composites among the high performance composites having economic and environmental advantages. In the field of technical utilization of plant fibers, flax fiber-reinforced composites represent one of the most important areas. On the other hand, lack of good interfacial adhesion and poor resistance to moisture absorption make the use of natural fiber-reinforced composites less attractive. In order to improve their interfacial properties, fibers were subjected to chemical treatments, namely, mercerization, silane treatment, benzoylation, and peroxide treatment. Selective removal of non-cellulosic compounds constitutes the main objective of the chemical treatments of flax fibers to improve the performance of fiber-reinforced composites. The objective of this study was to determine the effects of pre-treated flax fibers on the performance of the fiber-reinforced composites. Short flax fibers were derived from Saskatchewan-grown flax straws, for use in fiber-reinforced composites. Composites consisting of high-density polyethylene (HDPE) or linear low-density polyethylene (LLDPE) or HDPE/LLDPE mix, chemically treated fibers and additives were prepared by the extrusion process. Extrusion is expected to improve the interfacial adhesion significantly as opposed to simple mixing of the two components. The extruded strands were then pelletized and ground. The test samples were prepared by rotational molding. The fiber surface topology and the tensile fracture surfaces of the composites were characterized by scanning electron microscopy to determine whether the modified fiber-matrix interface had improved interfacial bonding. Mechanical and physical properties of the composites were evaluated. The differential scanning calorimetry technique was also used to measure the melting point of flax fiber and composite. Overall, the scanning electron microscopy photographs of fiber surface characteristics and fracture surfaces of composites clearly indicated the extent of fiber-matrix interface adhesion. Chemically treated fiber-reinforced composites showed better fiber-matrix interaction as observed from the good dispersion of fibers in the matrix system. Compared to untreated fiber-reinforced composites, all the treated fiber-reinforced composites had the same tendency to slightly increase the tensile strength at yield of composites. Silane, benzoylation, and peroxide treated fiber-reinforced composites offered superior physical and mechanical properties. Strong intermolecular fiber-matrix bonding decreased the high rate of water absorption in biocomposites. The incorporation of 10% untreated or chemically treated flax fibers also increased the melting point of composites. Further investigation is required to address the effect of increase in fiber content on the performance of composites.

Pure-breeding, early-flowering lines of flax, derived from treatment of germinating seeds with 5-azacytdine in 1990, flower 7-13 days before controls, have fewer leaves, are shorter, and have hypomethylated total DNA, relative to control lines. This thesis examines the changes in DNA methylation levels in the cotyledons and shoot tips of early-flowering Royal flax lines (i.e. RE1 and RE2) and their control (RC) to determine the changes from 24 days to the onset of flowering (approximately 34 days in RE1 and RE2, and 52 days in RC). It also examines the question of whether DNA is methylated in the chloroplast genome of flax. Finally, the thesis looks at the differences in transcript abundance of the flowering genes LEAFY and TERMINAL FLOWER1 in RC and RE2. Methylation levels in RE1 and RE2 were found to be lower than in RC from 24 days of age to the onset of flowering and the levels of all three lines increase with tissue age and/or differentiation. In addition, buds of RE2 were hypomethylated relative to RC. If plants were placed in the dark prior to DNA extraction, hypomethylation was not seen in the total DNA of RE2. The chloroplast DNA of flax was found to be methylated, and RE2 chloroplast DNA was hypomethylated relative to RC. Differences in transcript levels of LFY were seen in RC and RE2 shoot tips, where a higher accumulation of transcript seen in RE2 compared to RC may be related to its earlier flowering time. In leaves, there was no significant difference in the transcript abundance of LFY between RC and RE2. TFL1 was detected in genomic DNA of RC and RE2; it was not detected in the cDNA of the two lines. In summary, compared to RC, hypomethylation was seen in the total DNA of RE2 plants grown under regular light conditions and the methylation levels in the all lines increased with age in shoot tips, cotyledons, and leaves. The chloroplast DNA of RE2 was also hypomethylated relative to that of RC. RE2 accumulated LFY transcript in shoot tips at flowering, which was not the case in RC. Although these ideas cannot be linked at this time, they are all likely related to the early-flowering phenotype.

Pure-breeding, early-flowering lines of flax, derived from treatment of germinating seeds with 5-azacytdine in 1990, flower 7-13 days before controls, have fewer leaves, are shorter, and have hypomethylated total DNA, relative to control lines. This thesis examines the changes in DNA methylation levels in the cotyledons and shoot tips of early-flowering Royal flax lines (i.e. RE1 and RE2) and their control (RC) to determine the changes from 24 days to the onset of flowering (approximately 34 days in RE1 and RE2, and 52 days in RC). It also examines the question of whether DNA is methylated in the chloroplast genome of flax. Finally, the thesis looks at the differences in transcript abundance of the flowering genes LEAFY and TERMINAL FLOWER1 in RC and RE2. Methylation levels in RE1 and RE2 were found to be lower than in RC from 24 days of age to the onset of flowering and the levels of all three lines increase with tissue age and/or differentiation. In addition, buds of RE2 were hypomethylated relative to RC. If plants were placed in the dark prior to DNA extraction, hypomethylation was not seen in the total DNA of RE2. The chloroplast DNA of flax was found to be methylated, and RE2 chloroplast DNA was hypomethylated relative to RC. Differences in transcript levels of LFY were seen in RC and RE2 shoot tips, where a higher accumulation of transcript seen in RE2 compared to RC may be related to its earlier flowering time. In leaves, there was no significant difference in the transcript abundance of LFY between RC and RE2. TFL1 was detected in genomic DNA of RC and RE2; it was not detected in the cDNA of the two lines. In summary, compared to RC, hypomethylation was seen in the total DNA of RE2 plants grown under regular light conditions and the methylation levels in the all lines increased with age in shoot tips, cotyledons, and leaves. The chloroplast DNA of RE2 was also hypomethylated relative to that of RC. RE2 accumulated LFY transcript in shoot tips at flowering, which was not the case in RC. Although these ideas cannot be linked at this time, they are all likely related to the early-flowering phenotype.