Abstract
BackgroundThe nutritional value of soybean oil is largely influenced by the proportions of unsaturated fatty acids (FAs), including oleic acid (OA, 18:1), linoleic acid (LLA, 18:2), and linolenic acid (LNA, 18:3). Genome-wide association (GWAS) studies along with gene expression studies in soybean [Glycine max (L.) Merr.] were leveraged to dissect the genetics of unsaturated FAs.ResultsA association panel of 194 diverse soybean accessions were phenotyped in 2013, 2014 and 2015 to identify Single Nucleotide Polymorphisms (SNPs) associated with OA, LLA, and LNA content, and determine putative candidate genes responsible for regulating unsaturated FAs composition. 149 SNPs that represented 73 genomic regions were found to be associated with the unsaturated FA contents in soybean seeds according to the results of GWAS. Twelve novel genes were predicted to be involved in unsaturated FA synthesis in soybean. The relationship between expression pattern of the candidate genes and the accumulation of unsaturated FAs revealed that multiple genes might be involved in unsaturated FAs regulation simultaneously but work in very different ways: Glyma.07G046200 and Glyma.20G245500 promote the OA accumulation in soybean seed in all the tested accessions; Glyma.13G68600 and Glyma.16G200200 promote the OA accumulation only in high OA germplasms; Glyma.07G151300 promotes OA accumulation in higher OA germplasms and suppresses that in lower OA germplasms; Glyma.16G003500 has the effect of increasing LLA accumulation in higher LA germplasms; Glyma.07G254500 suppresses the accumulation of LNA in lower OA germplasms; Glyma.14G194300 might be involved in the accumulation of LNA content in lower LNA germplasms.ConclusionsThe beneficial alleles and candidate genes identified might be valuable for improving marker-assisted breeding efficiency and exploring the molecular mechanisms underlying unsaturated fatty acid of soybean.
Highlights
The nutritional value of soybean oil is largely influenced by the proportions of unsaturated fatty acids (FAs), including oleic acid (OA, 18:1), linoleic acid (LLA, 18:2), and linolenic acid (LNA, 18:3)
The beneficial alleles and candidate genes identified might be valuable for improving marker-assisted breeding efficiency and exploring the molecular mechanisms underlying unsaturated fatty acid of soybean
A targeted Genome-wide association (GWAS) was used to analyze the genetic architecture of unsaturated FAs using only 1536 single nucleotide polymorphism (SNP) and 421 diverse accessions, and the results showed that 8, 12, and 5 Quantitative Trait Nucleotide (QTNs) were associated with Linoleic acid (LLA), Linolenic acid (LNA), and Oleic acid (OA) content [19]
Summary
The nutritional value of soybean oil is largely influenced by the proportions of unsaturated fatty acids (FAs), including oleic acid (OA, 18:1), linoleic acid (LLA, 18:2), and linolenic acid (LNA, 18:3). Soybean oil consists of saturated fatty acids (FAs), including palmitic acid (PA, 16:0) and stearic acid (SA, 18:0) and unsaturated FAs such as oleic acid (OA, 18:1), linoleic acid (LLA, 18:2), and linolenic acid (LNA, 18:3). Consumption of soybean oils with higher OA levels is desirable because this monounsaturated FA could improve storage time, which increases the price of the soybean oil and in the cost of generating unhealthy trans fat for humans [4]. The nutritional value of unsaturated FAs benefits humans, the high levels of LLA and LNA in soybean oil results in low oxidative stability and rapid rancidity, as well as reduces storage time of soybean oil [6]. The increase in OA and decrease in LLA and LNA contents could improve the quality of soybean oil for human consumption and has become an important goal of soybean breeders
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