Fatty ester development in reduced- and elevated-palmitate lines of soybean

Soybean [Glycine mar (L.) Merr.] lines are available that have been genetically modified to reduce and to elevate palmitate content in the seed oil, One objective of this study was to evaluate the changes in palmitate content that occur during seed development of reduced- and elevated-palmitate soybean genotypes. A second objective was to determine the relationship between the palmitate content of the leaves, stems, roots, and seeds of the soybean genotypes. The genotypes evaluated were 'Elgin 87', with a normal palmitate content of 110 g kg(-1); A18, a reduced-palmitate line with <45 g kg(-1); and A19, an elevated palmitate line with >250 g kg(-1). For the first objective, the seeds of each of the lines were harvested at 2-d intervals from 15 to 39 d after flowering (DAF) and 4-d intervals from 39 DAF until maturity during 1991 and 1992. Significant differences among the lines for palmitate content of the seeds were observed as early as 19 DAF. The increase in palmitate in A19 was accompanied by a decrease in oleate and linoleate content. The decrease in palmitate in A18 was accompanied by an increase in oleate content. For the second objective, there was a relationship between the palmitate content in the seed oil and that of the roots, leaves, and stems for each of the lines, A18, which had the lowest palmitate content in the seed oil, had the lowest palmitate content in roots, leaves, and stems. A19, which had the highest palmitate content in the seed on, had the highest palmitate content in the vegetative tissues studied. The results indicated that the mutant alleles in A18 and A19 are constitutively expressed.