Abstract
New flaxseed cultivars differing in seed mucilage content (MC) with low hull content (HC) represent an attractive option to simultaneously target the food and feed markets. Here, a genome-wide association study (GWAS) was conducted for MC and HC in 200 diverse flaxseed accessions genotyped with 1.7 million single nucleotide polymorphism (SNP) markers. The data obtained for MC and HC indicated a broad phenotypic variation and high (~70%) and a moderate (~49%) narrow sense heritability, respectively. MC and HC did not differ statistically between fiber and oil morphotypes, but yellow-seeded accessions had 2.7% less HC than brown-seeded ones. The genome-wide linkage disequilibrium (LD) decayed to r2 = 0.1 at a physical distance of ~100 kb. Seven and four quantitative trait loci (QTL) were identified for MC and HC, respectively. Promising candidate genes identified include Linum usitatissimum orthologs of the Arabidopsis thaliana genes TRANSPARENT TESTA 8, SUBTILISIN-LIKE SERINE PROTEASE, GALACTUROSYL TRANSFERASE-LIKE 5, MUCILAGE-MODIFIED 4, AGAMOUS-LIKE MADS-BOX PROTEIN AGL62, GLYCOSYL HYDROLASE FAMILY 17, and UDP-GLUCOSE FLAVONOL 3-O-GLUCOSYLTRANSFERASE. These genes have been shown to play a role in mucilage synthesis and release, seed coat development and anthocyanin biosynthesis in A. thaliana. The favorable alleles will be useful in flaxseed breeding towards the goal of achieving the ideal MC and HC composition for food and feed by genomic-based breeding.
Highlights
Flaxseed (Linum usitatissimum L.), one of the oldest crops, has been used as human food and animal feed since ancient times [1]
We performed genome-wide association study (GWAS) using a set of 771,914 single nucleotide polymorphism (SNP), identifying seven and four quantitative trait loci (QTL) for mucilage content (MC) and hull content (HC), respectively
Three of the QTL associated with HC contained plausible candidate genes related to seed coat and anthocyanin biosynthesis
Summary
Flaxseed (Linum usitatissimum L.), one of the oldest crops, has been used as human food and animal feed since ancient times [1]. Mucilage synthesis is tightly linked to seed coat development [5] and both tissues form the seed hull, a structure representing 37–48% of the seed weight [6,7] These two fractions, rich in polysaccharides, are components of the flaxseed meal, primarily used as a protein rich livestock and poultry feed [6,8]. Absorption of flaxseed meal s advantageous 31–45% protein content [9] may be hindered by mucilage and cell wall polysaccharides. This is due to the swelling capacity of polysaccharides in the digestive tract of monogastric animals that causes concomitant growth depression and reduced feed efficiency [7,10]. Crucial to decipher the genetic factors underlying these complex traits in order to accelerate the development of market-specific flaxseed cultivars
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