Expression and localization of foreign proteins in soybean and tobacco seed tissue

Abstract One major objective of this study was to determine the role of the soybean lectin 32 amino terminal sequence for proper protein processing and transport of genes placed under the control of the tissue-specific promoter regions. Lectin 32 amino terminal sequence is the amino terminal 32-amino acid peptide of the lectin coding region that is not part of the mature lectin protein found in the protein bodies of soybean (Glycine max) seeds. In order to study the first objective, tobacco plants were transformed with constructs containing the coding region of a bacterial {dollar}beta{dollar}-glucuronidase gene (commonly referred to as the GUS gene; gusA or uidA) inserted between the 5{dollar}spprime{dollar} (+/{dollar}-{dollar}32 amino terminal sequence) and 3{dollar}spprime{dollar} regulatory sequences of soybean lectin. Subcellular localization studies were conducted on the seeds of these transformed tobacco plants. The GUS activity and protein produced by the expression cassette without the 32 amino terminal sequence were found to be expressed in the cytoplasm. The GUS activity and protein produced by the expression cassette with the 32 amino terminal sequence were directed to the microsomal membranes and exported possibly to the protein bodies suggesting the possibility that the 32 amino terminal sequence also contains the vacuolar targeting information.; Another objective of this research was to test a transformation procedure for soybean with an expression vector containing a casein gene, under the control of the seed-specific lectin promoter. Soybean is one of several crop plants which are still difficult to transform even in the hands of plant transformation specialists. Transformation of soybean embryogenic suspension cultures was achieved via microprojectile bombardment method. Several independently transformed clones were obtained, but the problems of regenerating these clones into a plant are still be to be solved. Genomic southern blot analysis of these transgenic clones shows multiple integration events of the introduced genes.