Broad-spectrum resistance to pathogens and spoilage organisms is a major goal of plant molecular biologists. To provide broad-spectrum resistance to bacterial and fungal phytopathogens, a synthetic gene encoding a modified chimeric, cecropin-melittin cationic peptide (MsrA1), with broad-spectrum antimicrobial activity, was introduced into two potato (Solanum tuberosum L.) cultivars, Desiree and Russet Burbank, under the control of the duplicated-enhancer CaMV 35S promoter. The 34-amino acid peptide (MsrA1) comprises, 8 amino acids from cecropin A and 16 amino acids from melittin but with a modified hexapeptide N-terminus to dampen cytotoxicity. Incorporation was confirmed by PCR and DNA sequencing and expression by RT-PCR. Unusually stringent cocultivation bioassays of the resulting transgenic plants with phytopathogenic bacterial or fungal pathogens indicated powerful resistance to these phytopathogens. The morphology and yield of transgenic Desiree tubers were comparable to that of non-transformed plants. Tubers were shown to retain their resistance to bacterial infection after several months of storage. In Russet Burbank, expression of msrA1 also caused a lesion-mimic phenotype displayed during leaf and tuber development. Thus the expression of msrA1 confers a powerful, broad-spectrum, phytopathogen-resistant phenotype to transgenic potato plants and tubers, and provides a novel and highly flexible strategy for the creation of new generations of disease and spoilage resistant plants.
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Osusky, M., Osuska, L., Kay, W. et al. Cationic Peptide Expression in Transgenic Potato Confers Broad-Spectrum Resistance to Phytopathogens. Nat Biotechnol 17, 45 (1999). https://doi.org/10.1038/70416