Use of the gene of antimicrobial peptide cecropin P1 for producing marker-free transgenic plants

The marker-free transgenic tobacco plants carrying a synthetic gene encoding the antimicrobial peptide cecropin P1 (cecP1) under the control of the cauliflower mosaic virus 35S RNA promoter were produced. The binary vector pBM, free of any selective genes of resistance to antibiotics or herbicides intended for selecting transgenic plants, was used for transformation. The transformants were screened on a nonselective medium by detecting cecropin P1 in plant cells according to the antibacterial activity of plant extracts and enzyme immunoassay. According to the two used methods, 2% of the analyzed regenerants were transformants. The resulting marker-free plants displayed a considerably increased resistance to microbial phytopathogens—the bacterium Erwinia carotovora and fungus Sclerotinia sclerotiorum. Thus, the gene cecP1 can be concurrently used as a target gene and a screening marker. The utility of cecP1 as a selective gene for direct selection of transformed plants is discussed.