Soyabean (Glycine max) oil is the most important vegetable oil in the world, accounting for 28% of the world’s edible oil consumption. The oil content in soybean seeds is approximately 20% (w/w). It contains five FAs: palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1), linoleic acid (C18:2), and linolenic acid (C18:3), with average contents of 10%, 4%, 18%, 55%, and 13%, respectively. In plants, FAs are exclusively synthesized de novo in plastids. Acetyl-CoA carboxylase catalyzes the formation of malonyl-CoA from acetyl-CoA, and fatty acid synthase transfers the malonyl moiety to acyl carrier protein (ACP) and catalyzes the extension of the growing acyl chain with malonyl-ACP.2

 

Breeding for fatty acid manipulation can be achieved through traditional breeding. Molecular genetic techniques offer more precise control over fatty acid manipulation in soybean breeding. Researchers identify and characterize genes and metabolic pathways involved in fatty acid synthesis, desaturation, elongation, and regulation. Genetic engineering techniques, such as introducing desaturase and elongase genes, modifying regulatory genes, and combining multiple genetic modifications, allow for targeted manipulation of fatty acid composition.1

 

To develop transgenic soybean with high α-linolenic acid (ALA; 18:3) content, the FAD3-1 gene isolated from lesquerella (Physaria fendleri) was used. The increased content of 18:3 in the Pβ-con: PfFAD3-1 soybean (T1) resulted in a 52.6% increase in total fatty acids, with a larger decrease in 18:1 content than 18:2 content. The increase in 18:3 content was also maintained and reached 42% in the Pphas: PfFAD3-1 transgenic generation T2.4 CRISPR/Cas9 mutants was produced for the pair of FATB protein coding genes, GmFATB1a and GmFATB1b. The single gene mutants fatb1a or fatb1b, showed a significant decrease in palmitic acid and stearic acid content in both leaves and seeds. The double mutant fatb1a:1b resulted in a greater reduction in palmitic acid and stearic acid content than that in the single mutants, displayed growth defects, and had male sterility.3

Challenges in this field include addressing regulatory considerations, ensuring consumer acceptance and safety, and understanding potential environmental impacts associated with genetically modified crops. Advancements in technologies such as genome editing, systems biology, metabolic engineering, and synthetic biology hold promise for further enhancing fatty acid manipulation in soybean breeding. These technologies allow for precise modifications at the genetic level and offer opportunities to optimize fatty acid profiles in soybean varieties.            

 

R   EFERENCES:

1   1 CARDINAL, A.J., 2007. Molecular genetics and breeding for fatty acid manipulation in soybean. Plant Breeding Reviews, 30, pp.259-294.


2K   2ULKARNI, K.P., TAYADE, R., JO, H., SONG, J.T. AND LEE, J.D., 2021. Breeding Strategy for Improvement of Omega-3 Fatty Acid through Conventional Breeding, Genetic Mapping, and Genomics in Soybean. In Plant Breeding-Current and Future Views. IntechOpen.


3      3MA, J., SUN, S., WHELAN, J. AND SHOU, H., 2021. CRISPR/Cas9-mediated knockout of GmFATB1 significantly reduced the amount of saturated fatty acids in soybean seeds. International Journal of Molecular Sciences, 22(8), p.3877.


      4YEOM, W.W., KIM, H.J., LEE, K.R., CHO, H.S., KIM, J.Y., JUNG, H.W., OH, S.W., JUN, S.E., KIM, H.U. AND CHUNG, Y.S., 2020. Increased production of α-linolenic acid in soybean seeds by overexpression of Lesquerella FAD3-1. Frontiers in Plant Science, 10, p.1812.