Objectives
- Determine optimum conditions required for accelerated growth of flax for seed production and reduced generation time.
- Evaluate speed breeding to generate a RIL population for genetic mapping.
- Use speed breeding and field testing to generate pre-registration candidates via integrating the use marker assisted selection to pyramid genes and selection based on phenotypes.
Project Description
The goal of accelerated breeding is to combine desirable traits quickly, in a manner that allows for efficient development of novel genotypes in a cost-mindful way. The objectives of this research were to develop a speed breeding protocol for flax and to assess the potential utility to develop a large recombinant inbred line (RIL) population and two groups of novel genotypes, one via molecular marker-assisted selection (MMAS) and the other via visual selection. We tested the effects of increasing daylength, increasing day temperature, and combining increased daylength and high temperature on a variety of traits, including time to maturity. Using ten flax genotypes, the combined long-day and high temperature treatment proved to be the most effective way to accelerate plant development, creating an environment where plants can mature two to four weeks earlier than under normal conditions. We also compared rates of germination of seeds taken from plants under speed breeding conditions vs control conditions, and found that under speed breeding conditions, seeds can be harvested three to eleven days earlier than under normal conditions. We applied our speed breeding protocol, combined with high-density seeding and early harvest of individual mature bolls to develop a large RIL population of ~1300 individuals in a single growth chamber. Traditional approaches to develop an inbred population of this size require multiple chambers per generation, which substantially increases the costs and time required. Our approach allowed us to save at least one year in time and ~$36,000 in growth chamber rentals under current rate. We used our speed breeding protocol to successfully develop two groups of novel genotypes. Under our speed breeding protocol, we crossed an experimental line with short stature and large seeds (FMC77) and CDC Bethune. We performed selections to develop a short, large-seeded genotype with improved agronomic performance, relative to FMC77. Compared to CDC Bethune, plants destined for the field were 42-72% shorter, had 100-seed weights 190-214%, and total seed weights of 89-151%. The F5 genotypes with large seeds and short stature were grown at the Kernen Crop Research Farm (KCRF). We identified genotypes with improved agronomic performance relative to the FMC77 parent. For the second group of novel genotypes, we crossed French winter type flax ‘Adelie’ that carries powdery mildew resistance, with CDC Dorado, which has yellow seeds. We performed MMAS at the F2-F4 generations using assays for the Y gene that determines yellow seed coat colour, and a high-resolution melt (HRM) assay for the putative powdery-mildew resistance from Adelie. From 1,710 individuals F2, we reduced the population to 98 in F3, 24 in F4, and selected eight F5 lines for field testing in 2025. All genotypes under field conditions showed good agronomic performance overall, with yields and seed weights exceeding Adelie. Under our conventional program, this process of developing homozygous novel genotypes would take 4-5 years. Using our speed breeding method, we developed them in ~2 years. In this study, we successfully developed a speed breeding protocol suitable for a range of flax genotypes and have shown its efficacy in developing novel germplasm efficiently.
Grower Benefits
- We developed a successful speed breeding protocol that incorporates an extended day length and higher day temperature that can be used to quickly develop novel genotypes for both research and breeding purposes.
- We developed a large research population of ~1300 RILs in ~16 months; compared to traditional RIL population development in the program, our speed breeding method saved approximately a year in time and ~$36,000 by growing plants in high density in a single chamber rather than spreading out the population over many chambers.
- In less than three years we developed two homozygous sets of novel genotypes that incorporate traits of interest from non-Canadian germplasm and improved agronomic performance relative to the non-Canadian parent and showed that the speed breeding protocol can be combined with MMAS and traditional phenotypic selection.
