Edward O. Kenaschuk

Variability in anticancer lignan levels in flaxseed

Flaxseed and its major mammalian lignan precursor secoisolariciresinol diglycoside have been shown to be protective against chemically induced carcinogenesis in animal models. Although flaxseed is the richest source of mammalian lignan precursors, it is not known whether these levels vary with source. Thus the objective of this study was to determine how lignan levels in flaxseed are affected by variety, growing location, harvest year, and seeding time. Ten varieties of flaxseed (AC Linora, Andro, Flanders, Linott, McGregor, Noralta, NorLin, NorMan, Somme, and Vimy) were subjected to 1) in vitro fermentation with human fecal inoculum for 24 hours under anaerobic conditions to assess mammalian lignan production and 2) high-performance liquid chromatography (HPLC) analysis for secoisolariciresinol levels. Three of these varieties (Linott, McGregor, and NorLin) were grown in four locations, seeded early (May) for three different years, and, in one year, seeded early (May) or late (June). Significant differences in lignan production were observed among the different varieties, ranging from 0.96 mumol/g for Linott to 3.15 mumol/g for Somme flaxseed (p < 0.05). Growing location had significant effects on lignan production from all three varieties. Harvest year significantly affected only the Linott variety (p < 0.05), whereas seeding time had no effect. A significant correlation (r = 0.572, p < 0.003) was observed between lignan values obtained from HPLC and in vitro fermentation methods, indicating that HPLC analysis of flaxseed may be used as a predictor of its lignan production levels. Differences due to variety, harvest location, and harvest year of flaxseed should be taken into consideration when tumorigenesis studies are designed.

Influence of genotype on chemical composition and rheological properties of flaxseed gums

Flaxseed gums extracted from different genotypes of flaxseed varied in chemical composition of their constituent polysaccharides. This difference in polysaccharide composition was responsible for their broad diversity in rheological behaviours as measured by small strain oscillatory rheological tests. Twelve flaxseed cultivars from two colour groups (yellow and brown, six of each) were examined in detail. The chemical composition and structure of flaxseed gums were determined by 13C NMR spectroscopy and monosaccharide analysis. Flaxseed gums appeared to follow a general rule that those containing higher amounts of arabinoxylans (neutral polysaccharides) exhibited shear thinning flow behaviour and ‘weak gel’-like properties. Those containing a higher amount of acidic polysaccharides (rhamnose, galacturonic acid) exhibited weaker rheological properties typical of viscoelastic fluid. Gums extracted from yellow seeds exhibited stronger rheological properties than those from the brown group. Of all the cultivars examined, aqueous dispersions of gum extracted from breeding line 84495 exhibited the highest apparent viscosity and storage modulus G′.

Plant regeneration from anther culture in Canadian cultivars of flax (Linum usitatissimum L.)

The effect of culture of anthers at 35 °C for one to four days prior to culture at 25 °C in darkness, genotype, anther orientation on callus induction and shoot regeneration in anther culture of flax was investigated. The influence of type and concentrations of cytokinins in the regeneration medium on shoot regeneration was also investigated. The results suggested that culture of anthers at 35 °C prior to continuous culture at 25 °C in darkness did not significantly improve the percentage of anthers producing calli. However, culture of anthers at 35 °C for one day significantly increased the overall efficiency of regeneration compared to no culture temperature treatment. Genotypic effects were significant for the percentage of anthers producing calli and the overall efficiency of regeneration. Anther orientation showed no significant differences. The regeneration medium containing 4.5 μM zeatin had significantly higher percentage of calli forming shoots than the same basal medium containing 0.01 μM TDZ. The importance of these findings for flax breeding was discussed.

Flavonoid content of flaxseed. Influence of cultivar and environment

SummaryTwo studies, one with four cultivars grown at four locations during 1989 to 1993, and the second with a transgenic and its non-transformed parent cultivar grown at three locations for three years, were undertaken to explore the variation in total flavonoid content of flaxseed (Linum usitatissimum). Results of the analyses of variance for the first study showed significant cultivar as well as environmental effect on flavonoid content. Cultivar NorLin displayed the highest flavonoid content across the sites with a mean of 71 mg/100 g, and Omega, a yellow-seeded flaxseed cultivar, the lowest with a mean of 35 mg/100 g. There was no significant difference between a transgenic flaxseed and its non-transformed parent for total flavonoid content except for one location in 1991. Flavonoid content was inversely related to the protein content and there was a weak positive correlation between flavonoid and oil levels.

Identification of microspore-derived plants in anther culture of flax (Linum usitatissimum L.) using molecular markers

Abstract The microspore origin of anther-culture-derived plants of flax was determined using inter-simple sequence repeat (ISSR) and randomly amplified polymorphic DNA (RAPD) markers. Polymorphic fragments between the two parents of the F1 donor plants were identified and their segregation patterns in anther-culture-derived plants were used to elucidate the origin of those plants and to determine the degree of independence of plants regenerated from the same callus. Using one ISSR primer (UBC 889) and two RAPD primers (UBC 556 and 561), 12 out of 16 plants were unequivocally identified as being derived from microspores. Plants derived from the same callus had identical PCR patterns at five polymorphic loci and thus were likely derived from the same microspore. Therefore, it is proposed that the number of calli forming shoots be used to describe the anther culture efficiency in flax.

Response of flax genotypes to doubled haploid production

Forty-four flax genotypes with a diverse genetic background were evaluated for anther culture response using a standard anther culture protocol in order to determine the feasibility to initiate a routine haploid production system in applied breeding programs. A strong genotype effect on callus induction and shoot regeneration in anther culture was found in this study. A number of genotypes, including two low cadmium content lines 96-11785 and 96-11826, a high oil content line 96-22109 and a high linolenic acid content line M 4919 were identified as highly responsive. The impact of the findings in this study on flax breeding was discussed.

Effect of sucrose concentration on elongation of shoots from flax anther culture

Anther culture is considered as the most successful method of producing doubled haploid plants in flax. The efficiency of shoot regeneration from anther culture has been improved dramatically by optimizing culture temperature and callus induction medium. However, shoot elongation has become increasingly the limiting factor for further improvement of the overall efficiency of doubled haploid production. The effect of sucrose con- 21 centration on shoot elongation was investigated in this study. The medium containing 10 g l sucrose produced longer and more vigorous shoots than the same medium containing other concentrations of sucrose. The possible physiological basis of sucrose on shoot elongation in flax was discussed.