Project Description
Saskatchewan is the leading producer of flaxseed in Canada and the largest exporter of flax seed in the World. Flax Canada 2010 Inc has developed a national strategy “for total utilization of flax for food, feed, fibre, health, and industrial uses”. This will result in more flax being grown in Saskatchewan and more value added opportunities for the crop in Saskatchewan.
In Canada, flax seed colour is used to identify the two main market types. Traditional, high linolenic acid flax must have brown seed; solin or zero linolenic acid flax must be yellow-seeded (Mittapalli and Rowland, 2003). There is potential to develop markets for flax high in omega-3 (linolenic acid), which is important in ever growing human and animal health market. Mittapalli and Rowland (2003) elucidated the allelic-gene relationship of the dominant yellow gene, the variegated recessive gene, and unknown spontaneous recessive yellow genes in flax. Segregation analysis indicated seed colour is governed by four independantly inherited loci, designated as the dominant Y1 allele and recessive g, d, and b1 alleles. The variegated seed colour is conditioned by a second recessive allele of the b1 locus, designated as b1vg. The recessive genes (g, d, and b1vg), when homozygous recessive, are epistatic to the other loci carrying dominant alleles. Our breeding program includes five recombinant inbred line (RIL) populations derived from single seed descent of large F2 populations involving crosses of diverse flax lines with different seed colour genes and a common parent, CDC Bethune (a high yielding and popularly grown flax variety). Single bolls/seed were retained from each plant to produce subsequent generations, which were similarly advanced by single seed descent to an advanced generation (e.g., F6). This selection technique allows homozygosity to be achieved in a short time and the fixing of traits within the RILs. No selection was conducted within a population, so the RIL populations segregate (differ) for the traits in the contrasting parental lines. These RILs are ideal for the genetic study of seed colour and other seed traits. Genetic mapping of DNA markers for the different seed colour genes in these RIL populations, grown in different environments across years, will allow us to estimate the genetic and environmental components of seed colour and other traits as well as discover any linkages between different seed characteristics.
The CDC flax breeding program has developed 3000 Recombinant inbred lines (RILs) of five crosses involving five lines with different seed colour genes and CDC Bethune, as well as, 15,000 M2 line of EMS (ethyl methane sulphonate) treated seed of CDC Bethune for genetics study.
Variation in days to flowering was normally distributed within the 5 RIL populations. There were RILs within each population earlier or later flowering than the parental lines, suggesting the presence of transgressive segregants. Variation in flower colour, size and shape were apparent within RIL populations where parental lines differed in any of these morphological characteristics. Variation in plant height was normally distributed within the 5 RIL populations. Phenotypic variation in fatty acid profile was evident with the 5 RIL populations. RILs are observed at the extremes of the parental lines for fatty acid profile for each population. The phenotypic data suggests that the 104 RILs of each population grown in 2009 is representative of the phenotypic diversity of the 3000 RILs of five crosses involving CDC Bethune and five lines with different seed colour genes. Cf. figures 9 to 13 illustrates variation between and within the different RIL populations for seed colour traits. Genotypes segregated into two groups for parameters b* (blue to yellow) and L* (whiter to blacker) in RIL populations derived CDC Bethune crossed to either YSED18R2 Y1Y1, S95407R110 gg or Crystal Yellow R434 b1b1. There was a range of phenotypes from parameter a* (green to red) for all 5 populations. No clear segregation of phenotypes for parameters b* and L* is exhibited in RIL populations derived from CDC Bethune crossed with either G-1186/94R218 dd or M96006R326 b1vgb1vg. A normal distribution for seed yield was exhibited in each RIL population. Phenotypic data collected on RILs grown in yield trials in 2010 indicate variation in crop phenology, plant height, flower colour, oil, protein content and omega-3 fatty acid content. RILs varied in seed colour based on the different parameters used to quantify this trait. An ADF funded project is underway to identify DNA markers for the different seed colour genes in these recombinant inbred line (RIL) populations segregating for seed colour. This phenotypic information in combination with developed DNA molecular markers will be used for Quantitative Trait Loci (QTL) analysis of key seed traits of flax. Knowledge generated from this research will inform the breeding of flax varieties with unique and useful combinations of fatty acids and seed colour.
