Plasmid 2013 May 23;69(3):249-56. Epub 2013 Jan 23.
Genetics Department, Faculty of Agriculture, Zagazig University, Egypt.
Agrobacterium-mediated transformation of plants has enhanced our ability to progress more rapidly in plant genetic engineering. Development of binary vectors for Agrobacterium has played a major role in advancing plant biology. Here, we report new features added to the Gateway-compatible vector pGWB533 for promoter testing with the reporter gene encoding β-glucuronidase (GUS). The original vector contains the spectinomycin/streptomycin adenylyltransferase (aadA) gene for bacterial selection and the hygromycin phosphotransferase gene (hpt) for transformed plant selection. However, some bacterial strains used to transform plants, such as Agrobacterium rhizogenes strain K599, have elevated tolerance to spectinomycin and streptomycin, thus making bacterial selection of pGWB533 inefficient. Although pGWB533 confers chemical selection for transgenic plants using hygromycin resistance, the plasmid has no visual marker that enables visual selection of transformed plants or transgenic tissue. In this regard, adding a gene to constitutively express green fluorescent protein (eGFP) makes it easier to visually select the transformed tissue and trim out the non-transformed. In this report we describe a series of vectors, pJan25S (NCBI: KC416200), pJan25T (NCBI: KC416201) and pJan25X (NCBI: KC416202), that are enhancements of pGWB533 for promoter testing. All three vectors contain the gene encoding eGFP as a visual marker for transformed tissue. However, in pJan25S and pJan25T, eGFP is controlled by the rolD promoter for root-specific expression, while in pJan25X it is controlled by the CaMV35S promoter for constitutive expression in all plant tissues. Spectinomycin and streptomycin resistance remains in pJan25S for bacterial selection; however, pJan25T and pJan25X contain the gene encoding tetracycline resistance (tet) for bacterial selection. These changes resulted in enhanced vectors with better visual and chemical selection that should have broad application in promoter studies.