Iwate Biotechnology Research Center, Narita, Kitakami, Iwate 024-0003, Japan
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Accepted 29 October 2000.
A recombinant plasmid, pTXS.TH, was constructed to express the gene-encoding wasabi (Wasabia japonica) defensin with the potato virus X (PVX) vector. pTXS.TH allows the expression of defensin in the host Nicotiana benthamiana, and the defensin protein WT1 can be purified from virus-infected leaves by heat treatment and affinity chromatography. WT1 exhibits strong antifungal activity toward the phytopathogenic fungi Magnaporthe grisea(50% inhibitory concentration [IC50] = 5 μg/ml) and Botrytis cinerea (IC50 = 20 μg/ml) but is weakly active against the phytopathogenic bacterium Pseudomonas cichorii. This virus-mediated expression system is a rapid and efficient method to produce and characterize antimicrobial proteins in plants. It is particularly useful for the study of proteins that are difficult to produce with other expression systems.
© 2001 The American Phytopathological Society