Mutations in soybean microsomal omega-3 fatty acid desaturase genes reduce linolenic acid concentration in soybean seeds

One major locus (Fan) and several minor loci have been shown to contribute to the linolenic acid level in soybean [Glycine max (L.) Merr.] seeds. The Fan gene encodes a microsomal omega-3 fatty acid desaturase (Arabidopsis FAD3 homolog), and soybeans contain three FAD3 genes. The objective of this work was to characterize candidate soybean FAD3 genes from low linolenic acid soybean lines and associate those alleles with the trait. Mutations in two of the three soybean FAD3 genes were identified, and genotypes with the mutant alleles conferred a reduction of over two thirds of the linolenic acid present in the seed. The two mutant genes contributed unequally but additively to the phenotype. The results demonstrated that the mutant genotype can be identified with mutation-specific molecular markers in the F-2 generation, and the low linolenic acid trait will be stably inherited in subsequent generations.