Changes in storage protein composition on genetic removal of Kunitz trypsin inhibitor maintain protein content in soybean (Glycine max)

Abstract Genetic removal of Kunitz trypsin inhibitor (KTI), a proteinaceous anti-nutritional factor, in soybean is anticipated to cause loss in protein content. In the present study, marker-assisted survey of 180 recombinant inbred lines (RILs) developed from the cross KTI+ve (‘SL525’) × KTI-free parent (‘NRC101’) in tandem with quantification of protein content led to the identification of KTI-free RILs with normal-protein content. SDS-PAGE analysis of KTI-free parent, KTI+ve parent, low-protein KTI-free, and 2 normal-protein KTI-free RILs showed random increase and decrease in the concentration of different subunits of glycinin (11S), β-conglycinin (7S) and other storage protein in the normal-protein KTI-free RILs compared to KTI+ve parent. KTI-free RILs with normal-protein content showed higher concentration of acidic and basic subunits of 11S and β-subunit of 7S fraction compared to the low-protein KTI-free RIL and KTI-free parent. The study suggested that it is possible to breed KTI-free soybean without reducing the protein content.