Characterization of a new GmFAD3A allele in Brazilian CS303TNKCA soybean cultivar

Abstract

We molecularly characterized a new mutation in the GmFAD3A gene associated with low linolenic content in the Brazilian soybean cultivar CS303TNKCA and developed a molecular marker to select this mutation. Soybean is one of the most important crops cultivated worldwide. Soybean oil has 13% palmitic acid, 4% stearic acid, 20% oleic acid, 55% linoleic acid and 8% linolenic acid. Breeding programs are developing varieties with high oleic and low polyunsaturated fatty acids (linoleic and linolenic) to improve the oil oxidative stability and make the varieties more attractive for the soy industry. The main goal of this study was to characterize the low linoleic acid trait in CS303TNKCA cultivar. We sequenced CS303TNKCA GmFAD3A, GmFAD3B and GmFAD3C genes and identified an adenine point deletion in the GmFAD3A exon 5 (delA). This alteration creates a premature stop codon, leading to a truncated protein with just 207 residues that result in a non-functional enzyme. Analysis of enzymatic activity by heterologous expression in yeast support delA as the cause of low linolenic acid content in CS303TNKCA. Thus, we developed a TaqMan genotyping assay to associate delA with low linolenic acid content in segregating populations. Lines homozygous for delA had a linolenic acid content of 3.3 to 4.4%, and the variation at this locus accounted for 50.83 to 73.70% of the phenotypic variation. This molecular marker is a new tool to introgress the low linolenic acid trait into elite soybean cultivars and can be used to combine with high oleic trait markers to produce soybean with enhanced economic value. The advantage of using CS303TNKCA compared to other lines available in the literature is that this cultivar has good agronomic characteristics and is adapted to Brazilian conditions.

GmFAD3A, A ω-3 Fatty Acid Desaturase Gene, Enhances Cold Tolerance and Seed Germination Rate under Low Temperature in Rice

“…Genes controlling the oleic acid and PUFA contents in soybean seed oil have been characterized, containing the two oleate desaturase genes GmFAD2-1A and GmFAD2-1B and three linoleate desaturase genes GmFAD3A, GmFAD3B, and GmFAD3C [11,12]. Mutation of GmFAD3 resulted in lower linolenic acid content (from 7% to 10%) [10,13]. A tobacco FAD3 expressed in rice could increase α-linolenic acid (ALA, C18:3) level up to 2.5-fold [14].…”

Identification of a Potential Gene for Elevating ω-3 Concentration and Its Efficiency for Improving the ω-6/ω-3 Ratio in Soybean

“…FAD3 genes are responsible for the conversion of LA into ALA in the fatty acid biosynthetic pathway. Previous studies have supported the role of FAD3 genes in ALA concentration via the discovery of mutant alleles of FAD3 genes that reduce levels of ALA for new genetic resources for soybean. − The combination of fad3a and either fad3b ( Glyma.02g227200 ) or fad3c ( Glyma.18g062000 ) leads to ∼3% ALA in soybean oil. − Soybean lines with 1% ALA were developed using the combination of all three FAD3 mutant alleles . In addition, expression levels of FAD3A are significantly higher than those of FAD3B and FAD3C in the developing seed stages .…”

“…Novel genetic resources selected from natural variations or induced by chemical mutagenesis have been used previously to alter fatty acid profiles in soybean breeding programs. − The benefit of mutation breeding is that changes induced by mutagens are stable and heritable to subsequent generations. Chemical mutagenesis has been successfully used to generate novel genetic diversity in soybean. , Our previous study revealed that ethyl methanesulfonate (EMS) mutagenesis of a soybean cultivar, Pungsannamul, resulted in a soybean mutant line, PE2166, with an elevated concentration of ALA fatty acid .…”

TILLING-by-Sequencing+ to Decipher Oil Biosynthesis Pathway in Soybeans: A New and Effective Platform for High-Throughput Gene Functional Analysis

“…Within the soybean genome, four GmFAD3 genes have been previously identified as GmFAD3A (Glyma.14g194300), GmFAD3B (Glyma.02g227200), GmFAD3C (Glyma.18g062000), and GmFAD3D (Glyma.11g174100) [ 27 , 28 ]. A series of novel allelic variations in GmFAD3A have been reported as a source that reduces linolenic acid content [ 29 , 30 ]. Reinprecht et al [ 31 ] isolated a low linolenic acid mutant line (RG10) resulting in a truncated GmFAD3A protein and a splicing mutation at the GmFAD3B.…”