Inheritance of reduced linolenic acid content in soybean seed oil

Abstract

 Linolenic acid is the unstable component of soybean [Glycine max (L.) Merr.] oil that is responsible for the undesirable odors and flavors commonly associated with poor oil quality. Two mutants, M-5 and KL-8, have been identified that have lower linolenic acid levels in the seed oil than the ‘Bay’ cultivar. Our objective was to determine the relationships between the genetic systems controlling linolenic acid in these mutants. Reciprocal crosses were made between the mutants and ‘Bay’, and between the two mutants. No maternal effect for linolenic acid content was observed from the analysis of F₁ seeds in any of the crosses. The data for linolenic acid content in F₂ seeds of M-5בBay’ and KL-8בBay’ crosses satisfactorily fit a 1 : 2 : 1 and 3 : 1 ratio, respectively. For the M-5×KL-8 cross, segregation observed from the analysis of F₂ seeds for linolenic acid content satisfactorily fit a ratio of 3 more than either mutant: 12 within the range of the two mutants: 1 less than either mutant. The segregation ratio of F₂ seeds and the segregation of F₃ seeds from F₂ plants indicated that M-5 and KL-8 have alleles at different loci that control linolenic acid content. The allele in KL-8 has been designated as fanx (KL-8) to distinguish it from fan (M-5). The low linolenic acid segregates with the genotype fanfanfanxfanx provide additional germplasm to reduce the linolenic acid content from the seed oil of soybean.