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Expression of a Truncated Form of Ribosomal Protein L3 Confers Resistance to Pokeweed Antiviral Protein and the Fusarium Mycotoxin Deoxynivalenol

August 2005 , Volume 18 , Number  8
Pages  762 - 770

Rong Di and Nilgun E. Tumer

Biotechnology Center for Agriculture and the Environment and the Department of Plant Biology and Pathology, Cook College, Rutgers University, New Brunswick, New Jersey 08901-8520, U.S.A.

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Accepted 24 March 2005.

The contamination of important agricultural products such as wheat, barley, or maize with the trichothecene mycotoxin deoxynivalenol (DON) due to infection with Fusarium species is a worldwide problem. Trichothecenes inhibit protein synthesis by targeting ribosomal protein L3. Pokeweed antiviral protein (PAP), a ribosome-inactivating protein binds to L3 to depurinate the α--sarcin/loop of the large rRNA. Plants transformed with the wild-type PAP show lesions and express very low levels of PAP because PAP autoregulates its expression by destabilizing its own mRNA. We show here that transgenic tobacco plants expressing both the wild-type PAP and a truncated form of yeast L3 (L3δ) are phenotypically normal. PAP mRNA and protein levels are very high in these plants, indicating that L3δ suppresses the autoregulation of PAP mRNA expression. Ribosomes are not depurinated in the transgenic plants expressing PAP and L3δ, even though PAP is associated with ribosomes. The expression of the endogenous tobacco ribosomal protein L3 is up-regulated in these plants and they are resistant to the Fusarium mycotoxin DON. These results demonstrate that expression of an N-terminal fragment of yeast L3 leads to trans-dominant resistance to PAP and the trichothecene mycotoxin DON, providing evidence that both toxins target L3 by a common mechanism.

Additional keywords: Fusarium head blight , translation inhibitor .

© 2005 The American Phytopathological Society