Exploring SoySNP50K and USDA Germplasm Collection Data to Find New QTLs Associated with Protein and Oil Content in Brazilian Genotypes.

Genetic diversity within a germplasm collection plays a vital role in the success of breeding programs. However, comprehending this diversity and identifying accessions with desirable traits pose significant challenges. This study utilized publicly available data to investigate SNP markers associated with protein and oil content in Brazilian soybeans. Through this research, twenty-two new QTLs (Quantitative Trait Loci) were identified, and we highlighted the substantial influence of Roanoke, Lee and Bragg ancestor on the genetic makeup of Brazilian soybean varieties. Our findings demonstrate that certain markers are being lost in modern cultivars, while others maintain or even increase their frequency. These observations indicate genomic regions that have undergone selection during soybean introduction in Brazil and could be valuable in breeding programs aimed at enhancing protein or oil content.

Reference Genes and Expression Analysis of Seed Desaturases Genes in Soybean Mutant Accessions.

Soybean oil is the second most-produced vegetable oil worldwide. To enhance the nutritional quality and oxidative stability of soybean oil, many soybean breeding programs are trying to increase oleic acid content and reduce linoleic and linolenic acid contents. The fatty acid profile of soybean oil is controlled by many genes, including those which code for omega-3 and omega-6 desaturases. Mutations in GmFAD2-1 and GmFAD3 genes are widely studied and their combinations can produce soybean oil with high oleic and low linoleic and linolenic content. However, few studies evaluate the effect of these mutations on gene expression. Therefore, the present study sought to identify reference genes, evaluate the expression of GmFAD2-1 and GmFAD3 seed desaturase genes in thirteen wild-type and mutated soybean accessions, and associate the expression patterns with fatty acid composition and with the GmFAD2-1 and GmFAD3 genotypes. GmCONS7 and GmUKN2 were identified as the best reference genes for combined use to normalize data. The GmFAD2-1A mutation of PI603452 accession was associated with a decrease in gene expression of GmFAD2-1A; however, downregulation may not be due to the truncated enzyme structure alone. These results suggested that there are factors other than GmFAD2-1A and GmFAD2-1B that have a considerable effect on oleic content, at least in soybeans with mutations in these two genes.

Characterization of a new GmFAD3A allele in Brazilian CS303TNKCA soybean cultivar.

KEY MESSAGE: 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.