The invention overcomes the deficiencies of the art by providing a soybean plant with non-transgenic mutations conferring decreased .alpha.-subunit of .beta.-conglycinin content and increased .alpha.'-subunit content of .beta.-conglycinin in seed. Moreover, the invention provides an agronomically elite soybean plant with non-transgenic mutations conferring a gyclinin null phenotype, increased .beta.-conglycinin content, and increased .alpha.'-subunit content of .beta.-conglycinin in the seed. The invention also provides derivatives, and plant parts of these plants and uses thereof. Methods for producing such plants are also provided.