Alteration of Seed Storage Protein Composition in Soybean [Glycine max (L.) Merrill] Mutant Lines Induced by γ-Irradiation Mutagenesis

This study investigated the alteration of seed storage proteins in soybean mutants induced by γ-irradiation. Five soybean cultivars and four landraces were irradiated with 250 Gy of γ rays to induce variability. The seed storage protein profiles of 414 genetic fixed mutants (M12–M20) having excellent agricultural traits were analyzed by SDS-PAGE. Among the 414 mutants, 58 were identifed as lacking lipoxygenase, 89 lacking the α′ subunit, 113 lacking the α subunit, and 40 with an altered β subunit. One hundred and forty-nine mutants lacked the A3 subunit of glycinin. Fifty-four mutants showed higher trypsin inhibitor (TIA) activity, whereas 139 showed lower TIA activity compared to their original cultivars. The selected mutants with low amounts of antinutritional factors such as trypsin inhibitor, lipoxygenase, and α subunit will constitute genetic resources for improving soybean protein quality.