Novel FAD3 Mutant Allele Combinations Produce Soybeans Containing 1% Linolenic Acid in the Seed Oil

Soybean [Glycine max (L.) Merr.] oil typically contains about 7% of linolenic acid, an oxidatively unstable fatty acid that is undesirable for many food applications. For cooking oil, reduction of the linolenic acid content by partial hydrogenation produces trans fatty acids, which are now known to increase the risk of coronary heart disease. Genetic reduction of linolenic acid was achieved decades ago, and recently the molecular genetic basis for both 3% and 1% linolenic acid soybean germplasm was revealed to be combinations of mutations in three independent members of the soybean omega-3 fatty acid desaturase (FAD3) genes that corresponded to the fan1, fan2, and fan3 loci. When the mutant GmFAD3A and GmFAD3C genes are found in combination in the breeding line CX1512-44, the linolenic acid content is reduced to approximately 3% of the of the seed oil. When the mutant GmFAD3A and GmFAD3B genes are in combination in the breeding line RG-10, a similar fatty acid profile is produced with approximately 3% linolenic acid. The objective of this work was to determine the ability of different combinations of mutant FAD3 alleles from CX1512-44 and an RG-10-derived soybean line to produce less than 3% linolenic acid in the seed oil. The results indicated that novel combinations of mutations in the three FAD3 genes are capable of producing soybean seeds containing only 1% linolenic acid in the seed oil.