Protein, Oil, and Isoflavone Contents in Lipoxygenase- and Kunitz Trypsin Inhibitor-Deficient Soybean Seeds

Two traditional soybean cultivars, CAC-1 and Garimpo, two backcrossed-derived isolines lacking lipoxygenase (LOX^?KTI⁺), and two backcrossed-derived isolines lacking lipoxygenase and Kunitz trypsin inhibitor (LOX^?KTI^?) in the seeds were grown in São Gotardo and Paracatu, Brazil, and their protein, oil, and isoflavone contents were assessed. The loss of LOX or the combined loss of LOX and KTI brought about no significant changes in seed oil content. Significant decreases in seed protein content were observed in isolines of the CAC-1 genetic background, but not in isolines of the Garimpo background. Total isoflavone contents in LOX^?KTI⁺ and LOX^?KTI^? isolines were higher than those in the normal parental cultivars. Genetic eliminations also changed isoflavone composition. These results suggest that the genetic removal LOX and KTI may be an efficient approach to improve nutritional and nutraceutical values of soybean seeds, however, performances of null lines should be evaluated for undesirable modifications in seed composition.