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Title: Novel FAD3 mutant allele combinations produce soybeans containing 1% linolenic acid in the seed oil

item Bilyeu, Kristin
item Gillman, Jason
item LEROY, ALLEN - Beck'S Superior Hybrids, Inc

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/7/2010
Publication Date: 1/17/2011
Citation: Bilyeu, K.D., Gillman, J.D., Leroy, A. 2011. Novel FAD3 mutant allele combinations produce soybeans containing 1% linolenic acid in the seed oil. Crop Science. 51:259-264.

Interpretive Summary: Reducing linolenic acid, an unstable component of vegetable oil, in soybeans has become a primary objective in crop science research because of the health concerns surrounding the intake of trans fatty acids in the human diet. Conventional elimination of linolenic acid in soybean oil is through chemical hydrogenation, which creates trans fatty acids. Plant breeding efforts have centered on the desire to generate soybean varieties that produce good yields of stable oil which contain no trans fatty acids through genetic reductions in linolenic acid. In the work described in this manuscript, new soybean breeding lines containing only 1% linolenic acid were developed by combining mutant genes from two different 3% linolenic acid parental lines. We determined that novel combinations of three genes produced the 1% linolenic acid trait in soybean lines. Molecular marker assays were developed or improved to allow soybean breeders to efficiently capture the trait when developing new soybean varieties. The results expand the resources available to breeders that are trying to incorporate the low linolenic acid trait into other elite lines and to develop new varieties that will offer improved oil characteristics for the U.S. soybean products market.

Technical Abstract: Soybean is an important crop, with value derived from both the seed oil and protein-rich meal. Soybean oil typically contains a significant amount 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 independent members of the soybean omega-3 fatty acid desaturase (FAD3) genes. 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 indicate novel combinations of mutations in the three FAD3 genes are capable of producing soybean seeds containing only 1% linolenic acid in the seed oil.