Abstract The presence of stachyose and raffinose is considered an antinutritional factor for humans and monogastric animals, leading to limitations on soybean consumption as a protein source. In the present study, the effect of a mutation in the raffinose synthase 2 gene was measured on soybean quality traits. We used an F2 population with 168 soybean individuals developed by crossing four soybean lines and evaluated oil, protein, sucrose, raffinose, stachyose and fatty acid contents and their relationships. The mutation explained 69.61%, 51.81% and 31.96% of stachyose, raffinose and sucrose variation, respectively, and we were able to produce soybean with average stachyose of 0.18%. The low coefficients of determination for protein and oil indicate that the mutation can be used to increase sucrose and reduce raffinose and stachyose content without major changes in oil and protein.

Abstract The development of molecular markers is essential for improvement of soybean cultivars with modified fatty acid content. The objective of this study was to identify and validate SNP markers in candidate genes for fatty acid content in soybean. Six candidate genes (ARAF, PDAT, ABI3, FAD2-1b, FAD3B, and FAD3C) were selected. Alignment of gene sequences identified 25 SNPs and 3 INDELs. TSP primers were used to identify SNP alleles. 259 recombinant inbred lines (RILs) (FA22 / CD219) and 185 F2 progenies (A29 / Tucunaré) were tested for association of SNPs. An SNP for FAD3B was associated with variation in content of linoleic acid (R2 = 5.84%) and linolenic acid (R2 = 6.79%). In FAD3C, an SNP was associated with linoleic and linolenic acids (R2 of 9.21% and 18.51%, respectively). The ABI3 gene was associated with palmitic acid, with R2 = 5.41%. The SNP markers identified will be used in assisted selection for improvement of fatty acid content.

O objetivo deste trabalho foi identificar SNPs em genes associados ao conteúdo de ácidos graxos em soja e implementar a metodologia "high resolution melting" (HRM) para genotipagem desses SNPs. Os iniciadores HRM foram desenhados para discriminar os alelos SNPs em duas populações de mapeamento (RILs e F2) e seguiram o padrão esperado de segregação. Os SNPs do gene ABI associaram-se significativamente ao conteúdo de ácido esteárico (R² = 12,14), e os do gene FAD3B, aos conteúdos de ácido oleico (R² = 14,69) e linolênico (R² = 10,62). A técnica de genotipagem dos SNPs por HRM é eficiente na discriminação das classes genotípicas.

The objective of this work was to identify SNPs in genes associated with fatty acid content in soybean and to implement the high resolution melting (HRM) technique for SNP genotyping. HRM primers were designed to discriminate SNP alleles in two mapping populations (RILs and F2) and followed the expected pattern of segregation. The ABI gene SNPs were significantly associated with stearic acid content (R² = 12.14), and the ones from the FAD3B gene, with oleic (R² = 14.69) and linolenic acid (R² = 10.62) contents. The technique of genotyping SNPs by HRM is efficient to discriminate genotype classes.