Developmental Regulation of β-Conglycinin in Soybean Axes and Cotyledons

Abstract

Analysis of the expression of genes encoding the .beta.-conglycinin seed storage proteins in soybean [Glycine max] has been used to extend our understanding of developmental gene expression in plants. The .alpha., .alpha.'', and .beta. subunits of .beta.-conglycinin are encoded by a multigene family which is organ-specific in its expression. In this study we report the differentially programmed accumulation of the .alpha., .alpha.'', and .beta. subunits of .beta.-conglycinin. Multiple isomeric forms of each subunit are present in the dry seed, but the timing of their accumulation is unique for each subunit. The previously reported variation in amount of .alpha.'' and .alpha. subunits in axis and cotyledons is also reflected in the amount of subunit specific mRNA which is present in each tissue. The .beta. subunit, previously undetected in soybean axes, is found to be synthesized but rapidly degraded. These differences in .beta.-conglycinin protein accumulation may be reflected by the morphological differences observed in protein bodies between these two tissues.