Submitted to: Crop Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/17/2005
Publication Date: 8/1/2005
Citation: Bilyeu, K.D., Palavalli, L., Sleper, D., Beuselinck, P.R. 2005. Mutations in soybean microsomal omega-3 fatty acid desaturase genes reduce linolenic acid concentration in soybean seeds. Crop Science. 45:1830-1836. Interpretive Summary: More soybeans are produced than any other legume crop in the world. Soybeans have value from their high protein meal and abundant oil. Typically, soybean oil consists of undesirably high amounts of linolenic acid. There are soybean lines that have lower linolenic acid than is typically found, but breeding for low linolenic acid soybeans is complicated by the complex nature of the trait. Molecular markers specific to the desired traits are valuable tools in breeding programs. Our strategy relied on targeting three genes coding for enzymes that produce linolenic acid. In the low linolenic soybean lines, we identified mutations in two of the three targeted genes. Molecular markers were developed that distinguish the mutant genes from their normal counterparts. We analyzed the progeny from crosses between low linolenic and standard soybean lines, and found their seeds contained low levels of linolenic acid when the mutations were inherited. The results of this research will allow the efficient production of elite soybean varieties with the low linolenic acid trait and thus will benefit plant breeders and soybean producers.
Technical Abstract: One major locus (Fan) and several minor loci have been shown to contribute to the linolenic acid level in soybean seeds. The Fan gene encodes a microsomal omega-3 fatty acid desaturase (Arabidopsis FAD3 homologue), 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 the mutant genotype can be identified with molecular markers in the F2 generation, and the low linolenic acid trait will be stably inherited in subsequent generations.