Microsomal Omega-3 Fatty Acid Desaturase Genes in Low Linolenic Acid Soybean Line RG10 and Validation of Major Linolenic Acid QTL

Abstract

High levels of linolenic acid (80 g kg −1 ) are associated with the development of off-flavors and poor stability in soybean oil. The development of low linolenic acid lines such as RG10 (20 g kg −1 linolenic acid) can reduce these problems. The level of linolenic acid in seed oil is determined by the activities of microsomal omega-3 fatty acid desaturases (FAD3). A major linolenic acid QTL (>70% of variation) on linkage group B2 (chromosome Gm14) was previously detected in a recombinant inbred line population from the RG10 × OX948 cross. The objectives of this study were to validate the major linolenic acid QTL in an independent population and characterize all the soybean FAD3 genes. Four FAD3 genes were sequenced and localized in RG10 and OX948 and compared to the genes in the reference Williams 82 genome. The FAD3A gene sequences mapped to the locus Glyma.14g194300 [on the chromosome Gm14 (B2)], which is syntenic to the FAD3B gene (locus Glyma.02g227200) on the chromosome Gm02 (D1b). The location of the FAD3A gene is the same as was previously determined for the fan allele, that conditions low linolenic acid content and several linolenic acid QTL, including Linolen 3-3, mapped previously with the RG10 × OX948 population and confirmed in the PI 361088B × OX948 population as Linolen-PO (FAD3A). The FAD3B gene-based marker, developed previously, was mapped to the chromosome Gm02 (D1b) in a region containing a newly detected linolenic acid QTL [Linolen-RO(FAD3B)] in the RG10 × OX948 genetic map and corresponds well with the in silico position of the FAD3B gene sequences. FAD3C and FAD3D gene sequences, mapped to syntenic regions on chromosomes Gm18 (locus Glyma.18g062000) and Gm11 (locus Glyma.11g227200), respectively. Association of linolenic acid QTL with the desaturase genes FAD3A and FAD3 B, their validation in an independent population, and development of FAD3 gene-specific markers should simplify and accelerate breeding for low linolenic acid soybean cultivars.

Soybean (Glycine max) Haplotype Map (GmHapMap): a universal resource for soybean translational and functional genomics

“…Then, we investigated and confirmed the phenotypic impact of some of these LOF mutations in GmHapMap accessions (Figure 4 and Data S6). A frameshift mutation (frequency = 0.003) in the microsomal omega‐3 fatty acid desaturase ( FAD3A ), a key gene for linolenic acid synthesis in soybean seeds (Reinprecht and Pauls, 2016), was found in three accessions. Near‐infrared spectroscopy (NIRS) analysis of 36 soybean samples (with or without this LOF mutation) showed a significant ( P < 0.001) decrease in linolenic acid content in the mutant lines (4%) compared to the wild type (10%) (Figure 4a).…”

Meta-Analyses of QTLs Associated with Protein and Oil Contents and Compositions in Soybean [Glycine max (L.) Merr.] Seed

“…Efforts towards the genetic analyses of oil content and composition in soybean seed have been increasing due to the high demand of vegetable oils and its role in human health [ 6 ]. Due to the relatively short shelf life of soybean oil, the development of cultivars with modified oils possessing decreased linolenic acid and elevated oleic acid has become a critical breeding goal [ 7 ]. Additional modified oil targets have also been proposed, potentially resulting in high-value soybean oils [ 8 , 9 ].…”

Soybean Haplotype Map (GmHapMap): A Universal Resource for Soybean Translational and Functional Genomics

“…Then we investigated and confirmed the phenotypic impact of some of these LOF mutations in GmHapMap accessions ( Figure 4 ). A frameshift mutation (frequency=0.003) in the microsomal omega-3 fatty acid desaturase ( FAD3A ), a key gene for linolenic acid synthesis in soybean seeds (Reinprecht & Pauls 2016), was found in three accessions. Near-infrared spectroscopy (NIRS) analysis of four soybean lines (two with and without this LOF mutation) showed a significant ( P < 0.01) decrease in linolenic acid content in the mutant lines (4%) compared to the wild type (10%) ( Figure 4A ).…”