INHERITANCE OF REDUCED LINOLENIC ACID CONTENT IN SOYBEAN GENOTYPE-A16 AND GENOTYPE-A17

Reduction of linolenic acid content in soybean [Glycine max (L.) Merr.] oil is associated with improved odor and flavor characteristics. Germplasm with the lowest content of this fatty acid known in soybean (< 25 g kg-1) was identified in 1986 at Iowa State University from the cross of two mutant lines, A5 x A23. The objective of our study was to determine the genetic control of the reduced linolenic acid content in two lines from that cross, A16 and A17. The two lines with < 25 g kg-1 linolenic acid were mated reciprocally to 'Century 84' (77 g kg-1 linolenic), the mutant line C1640 (37 g kg-1 linolenic) and the parents, A5 and A23. There was no maternal effect when A16 and A17 were crossed to their parents, but a partial maternal effect was observed in crosses with Century 84 and C1640. In the crosses of A16 and A17 with Century 84, the segregation of the F2:3 lines satisfactorily fit a 1:14:1 ratio, which would be expected with the segregation of major genes at two independent loci. The data indicated that A16 and A17 obtained the fan(A5) allele from A5 and the fan2(A23) allele from A23. The continuous distributions observed in the A16 and A17 crosses with Century 84 indicated that minor genes and environmental effects also are important in the expression of linolenic acid content. Consequently, the low linolenic acid content of A16 and A17 can be considered a quantitative character for cultivar development programs.