Identification of Soybean (Glycine max L.) Segregants for Kunitz Trypsin Inhibitor and Lipoxygenase Free Gene Using Linked Molecular Markers

The presence of anti-nutritional factors such as Kunitz trypsin inhibitor and enzymes lipoxygenase, which contributes to the beany off-flavor, are key factors limiting consumer acceptance of soybeans. Kunitz trypsin inhibitor binds to and inhibits the activity of proteases (trypsin) found in the digestive systems of most mammals. The beany flavor in soybeans arises from the breakdown of PUFAs by lipoxygenase into hydroperoxide derivatives, which break down into various volatile compounds, creating the off-flavor. This undesirable flavor in soy products is linked to activity of lipoxygenase-1, lipoxygenase-2, and lipoxygenase-3 in soybean seeds, which are regulated by the dominant genes Lox1, Lox2, and Lox3, respectively. The current study involved molecular evaluation in the 21 F1s and segregating generation (31 F2s and 59 F3s) plants of three crosses viz., MACS 1520 × NRC 142, KDS 1201 × NRC 153 and KDS 1201 × TGX 709-50E. Total one hundred eleven plants from three crosses were analysed to check for dysfunctional alleles of KTI, LOX-2 and LOX-3 genes. The final findings showed that two plants out of them were triple null i.e. they do not have functional Kunitz trypsin inhibitor and Lipoxygenase 2 and Lipoxygenase 3 genes. Hence these two plants were absolutely promising for development of cultivar which triple null soybean. Six more plants were double null i.e. free from both KTI and LOX-2, therefore they can be used in homozygous genotype development in soybean breeding. It can lead to the attending the problem of soybean full protein utilization by human and ensures soybean long term storage.