Relationships and inheritance of linolenic acid and seed lipoxygenases in soybean crosses designed to combine these traits

To improve oxidative stability of soybean oil and reduce off-flavours, we previously developed low linolenic acid, lipoxygenase-free (LLA.3lx) soybean germplasm. The objectives of this study were to characterize the patterns of inheritance and determine the relationships between the low linolenic acid (LLA) trait derived from the lines RG10 and PI 361088B and seed lipoxygenase nulls (3lx) from a triple null line OX948 that were used to create the new LLA.3lx germplasm. Reciprocal crosses between RG10 and OX948 and between PI 361088B and OX948 were made and populations derived from them were evaluated for their fatty acid profiles and seed lipoxygenases (LX) at the F2, F5 and F6 generations. Both RG10 and PI 361088B contain a single gene that controls linolenic acid (LA) content with alleles acting in an additive manner. No significant cytoplasmic effects were observed on LA content. The LLA trait was highly heritable in both RG10 × OX948 (RO) and PI 361088B × OX948 (PO) crosses and stable in different environments (Belize and Ontario, Canada). The three seed LX were each controlled by single genes, but lipoxygenase 1 (Lx1) and lipoxygenase 2 (Lx2) were tightly linked. No significant correlations were observed between LA content and seed LX. The simple and independent inheritance of LA and seed LX in these crosses should simplify breeding for soybean cultivars that are resistant to oxidative degradation. Key words: Soybean, linolenic acid, lipoxygenase, inheritance, trait relationships