Inheritance of a Lipoxygenase-1 Allozyme in Soybean
1993
Pfeiffer, T. W. | Hildebrand, D. F. | Orf, J. H.
Three soybean [Glycine max (L) Merr.] seed lipoxygenase isozymes, involved in generating products which contribute to undesirable flavors in processed protein products, have been characterized genetically. The objective of this study was to determine the inheritance of an alternate lipoxygenase-1 allozyme, which has a more acidic isoelectric point than the normal allozyme (pI 5.79 vs. pI 5.85 for the normal allozyme). This alternate allozyme was originally seen in soybean strains L₂-3 and PI 86023, which are null for lipoxygenase-2, genotype lx₂ lx₂. A similar alternate allozyme was subsequently seen in ‘McCall’. The 1:2:1 F₂ segregation ratios from several crosses of “normal” allozyme × alternate allozyme parents indicated codominant inheritance of the two allozymes. The gene symbol Lxᵇ₁ is assigned to the allozyme with pI 5.79, and the gene symbol for the allozyme with pI 5.85 becomes Lxᵃ₁ This gives an allelic series at the lipoxygenase-1 locus Lxᵃ₁, Lxᵇ₁, and lx₁. The lx₁ and lx₂ loci are very tightly linked. Crosses between Lxᵃ₁ Lxᵃ₁ Lx₂Lx₂ and Lxᵇ₁ Lxᵇ₁ lx₂lx₂ genotypes would be designed to incorporate the lx₂lx₂ genotype into cultivars with improved protein flavor attributes for soyfood products. while phenotypes of Lx₂Lx₂ and lx₂lx₂ genotypes are indistinguishable in terms of lipoxygenase-2, the presence of two electrophoretic bands for lipoxygenase-1 (Lxᵃ₁ Lxᵇ₁) when the lipoxygenase-2 locus is also heterozygous makes it possible to identify individuals with the recessive lx₂ allele. The selection of heterozygotes can reduce the time needed to backcross the lx₂ allele. This paper 92-3-170 is published with the approval of the director of the Kentucky Agric. Exp. Stn.
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