Variation in the Low Molecular Weight Proteinase Inhibitors of Soybeans¹

Abstract

Two types of proteinase inhibitors exist in soybean [ Glycine max (L.) Merr.] seed. The first type is called the Kunitz trypsin inhibitor and the second is a group generally termed the Bowman‐Birk type inhibitors. The objectives of this study were to attempt to separate and purify the Bowman‐Birk type inhibitors in soybean seeds, and to screen for variants in the USDA Named Cultivar and Type Collections. Five Bowman‐Birk type inhibitors were separated from ‘Amsoy 71’ by anion exchange column chromatography. Soybean accessions were screened electrophoretically for variants of the inhibitors. Three variants were identified: 1) lines which appear to be missing fraction III electrophoretic band (F phenotype); 2) lines which appear to be missing fraction V electrophoretic band (S phenotype); and 3) lines in which both electrophoretic bands are present (SF phenotype). Most lines examined (71%) have the SF banding pattern. The S or F banding patterns are less common with only 26 and 3%, respectively, of the lines screened.