Expression of the β-subunit of β-conglycinin in seeds of transgenic plants.
Soybean (Glycine max (L.) Merr.) seeds contain the storage protein β-conglycinin, encoded by a multigene family. β-Conglycinin consists of three subunits; α', α, and β. A genomic clone for a β-subunit of β-conglycinin has been characterized by restriction-enzyme mapping and hybrid selected in-vitro translation followed by immunoprecipitation. In order to determine the developmental regulation of this β-subunit gene, its expression was studied in seeds of transgenic petunia (Petunia hybrida) and tobacco (Nicotiana tabacum L.) plants. The β-subunit expressed in seeds of petunia and tobacco was recognized by anti-β-conglycinin serum at a relative molecular mass of 53 000, equivalent to that of the native protein. Separation of the petunia-seed proteins by isoelectric focusing followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblot analysis showed that multiple isoelectric forms of the β-subunit were produced. There was approximately a twofold variation in the accumulation of the β-subunit protein in the mature seeds of transgenic petunia plants, each containing a single β-subunit gene. However, the level of protein accumulation in mature seeds and the amount of β-subunit mRNA in developing seeds was not correlated. Accumulation of the β-subunit protein in transgenic seeds was less than the α'-subunit protein that accumulated in transgenic petunia seeds containing a single α'-subunit gene and less than the amount of the β-subunit in mature soybean seeds which contain 8-13 β-subunit genes. In transgenic tobacco plants, the accumulation of the β-subunit protein in seeds was generally well correlated with the number of genes that were incorporated in the different transformants.
Department of Biology, Plant Biology Program, Washington University, 63130, St. Louis, MO, USA.
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Bray
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Naito
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Pan
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Anderson
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Dubé
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Beachy