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Title: Genetic improvement of the fatty acid biosynthesis system to alter the w-6/w-3 ratio in the soybean seed

Author
item KULKARNI, KRISHNANAND - Kyungpook National University
item KIM, MINSU - Kyungpook National University
item SONG, JONG TAE - Kyungpook National University
item Bilyeu, Kristin
item LEE, JEONG-DONG - Kyungpook National University

Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/6/2017
Publication Date: 11/1/2017
Citation: Kulkarni, K.P., Kim, M., Song, J., Bilyeu, K.D., Lee, J. 2017. Genetic improvement of the fatty acid biosynthesis system to alter the w-6/w-3 ratio in the soybean seed. Journal of the American Oil Chemists' Society. 94(11):1403-1410. https://doi.org/10.1007/s11746-017-3049-0.
DOI: https://doi.org/10.1007/s11746-017-3049-0

Interpretive Summary: Soybean is one of the most valuable sources for vegetable oil in the world because it imparts little of its own flavor and allows the flavors of other foods to predominate. The nutritional properties of vegetable oil vary due to the fatty acid components, and soybean oil has typically had an unbalanced ratio in the polyunsaturated fatty acids that is undesirable. The objective of this research was to alter the polyunsaturated fatty acid ratio in soybean oil through traditional breeding with genes that alter the accumulation of different fatty acids. The results demonstrated that an improved polyunsaturated fatty acid ratio could be achieved with the combination of gene variants of one of the two characterized fatty acid desaturase genes, genes that control the saturation level of the fatty acid, with variant genes from wild soybean. The impact of the results is a novel strategy for manipulating soybean oil quality using relatively few genes that can direct breeding to create new soybean varieties with this enhanced nutrition oil trait.

Technical Abstract: Soybean is an important source of vegetable oil beneficial for human consumption. Several studies have shown that a high '-6/'-3 ratio in edible oil adversely affects human health. Hence, the production of seed oils with a balanced '-6/'-3 ratio is recommended. The cultivated soybeans usually have 6-7:1 '-6/'-3 ratio in the seed oil. The objective of the present study was to reduce the '-6/'-3 fatty acid ratio in soybean through genetic improvement of the fatty acid biosynthesis system. In this study, we crossed S08-14717 (carrying FAD2-1A and FAD2-1B mutant alleles) with a wild soybean PI 483463 (containing ~15% a-linolenic acid, '-3) to generate a 2320 F2 population. The levels of five fatty acid components varied considerably in the 2320 F2:3 lines. To better understand the relationship between oleic and a-linolenic acid concentration, 114 lines were advanced to the F5:6 generation. The F5:6 lines with both FAD2 mutant alleles (aabb) had '-6/'-3 ratios of = 0.6, whereas lines having either the FAD2-1A or the FAD2-1B mutant allele (AAbb or aaBB) had '-6/'-3 ratios of 3.9 and 2.5, respectively. Thus, combinations of FAD2-1A and/or FAD2-1B mutant alleles, with a-linolenic acid-related gene/s from wild soybean offer an alternative methods to reduce '-6/'-3 fatty acid ratios in seed oil. This system of genetic modification of the '-6/'-3 fatty acid ratio may be applied to aid the development of desirable soybean cultivars.