Mutations in the soybean 3-ketoacyl-ACP synthase gene are correlated with high levels of seed palmitic acid

A complete understanding of the biosynthetic pathways involved in the formation of seed oils is an important step in the development of lines with useful oil profiles. Soybean oil has a number of industrial applications and is also a source of edible oils for human consumption. The elongation of palmitic acid to stearic acid by the 3-ketoacyl-ACP synthase II (KASII) enzyme represents a branch point in the pathway of oil biosynthesis in soybean. Three mutant soybean lines were identified which contained elevated levels of palmitic acid ranging from 12.9 to 15.6%. Candidate gene sequencing in these lines revealed that all three contain nucleotide changes in the coding sequence for the KASIIa gene. One mutation caused an early termination in the third exon of KASIIa, and two mutations resulted in amino acid changes in the KASIIa protein. These new mutant alleles of soybean KASIIa may be useful to fine-tune the composition of soybean seed oil using molecular breeding approaches.