EXPRESSION AND ACCUMULATION OF NORMAL AND MODIFIED SOYBEAN GLYCININS IN POTATO-TUBERS

Chimeric genes composed of the class I patatin promoter, A(1a)B(1b) pr eproglycinin cDNA and its modified versions (IV+4Met and V+4Met) conta ining four contiguous methionine codons and nopaline synthase gene ter minator were inserted into the genome of potato by Agrobacterium-media ted transformation. Transcripts of the chimeric genes were detected sp ecifically in tubers. Translational products were observed in parenchy ma cells of the tubers of potato plants transformed with the normal an d modified glycinin cDNAs. This distribution is consistent with the ex pression specificity of the patatin promoter. The expression levels of the normal and the modified glycinins were 0.2-1.0% of the total solu ble tuber proteins. Both the normal and the modified glycinins express ed in the tubers were present as proglycinin trimers. These results in dicate that the modifications in IV+4Met and V+4Met did not disrupt an y stage in the biosynthetic process of glycinin in potato tubers.