Genome-wide association analysis of mucilage and hull content in flax (Linum usitatissimum l.) seeds

The outer layer of flax seeds has hull and mucilage. Mucilage is made of heterogenous polysaccharides that abounds in the seed coat where it makes up to 10% of the seed weight. Mucilage and seed coat form the hull that accounts for 37-48% of the seed weight. In the meal, these two fractions hinder protein absorption by livestock and poultry. However, the food industry requires different seed quality traits because soluble fibres affecting intestinal transit are functional and preferred. To develop linseed varieties for different markets, it is essential to understand the genetic control of mucilage and hull contents in order to be able to manipulate them independently and in both directions. Here we looked at a collection of 200 flax lines and determined that mucilage content varied from 23-103 mg g-1 and hull content ranged from 36-48%. Yellow linseed had 2.7% lower hull content than brown linseed. DNA was extracted and each line was sequenced using a high throughput methods. The DNA sequences were analyzed and a set of nearly 800,000 variant positions were identified. Correlation-type analyses indicated that seven and four positions located on nine of the 15 chromosomes of flax influenced mucilage and hull content, respectively. Several possible genes were located near these positions and could be responsible to controlling mucilage and/or hull content in linseed. This marker information generated here can be used in breeding to design new cultivars with high mucilage for the food market or low mucilage and hull content for the feed industry.