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Identification of a Plum pox virus CI-Interacting Protein from Chloroplast That Has a Negative Effect in Virus Infection

March 2006 , Volume 19 , Number  3
Pages  350 - 358

I. Jiménez , L. López , J. M. Alamillo , A. Valli , and J. A. García

Department of Plant Molecular Genetics, Centro Nacional de Biotecnología (CSIC), Campus Universidad Autónoma de Madrid, 28049 Madrid, Spain

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Accepted 18 November 2005.

The cylindrical inclusion (CI) protein of potyviruses is involved in virus replication and cell-to-cell movement. These two processes should rely on multiple plant-virus interactions; however, little is known about the host factors that are involved in, or that may interfere with, CI functions. By using a yeast two-hybrid system, the CI protein from Plum pox virus (PPV) was found to interact with the photosystem I PSI-K protein, the product of the gene psaK, of Nicotiana benthamiana. Coexpression of PPV CI was shown to cause a decrease in the accumulation level of PSI-K transiently expressed in N. benthamiana leaves. To test the biological relevance of this interaction, we have analyzed the infection of PPV in N. benthamiana plants in which psaK gene expression has been silenced by RNA interference, as well as in Arabidopsis thaliana psaK knockout plants. Our results show that downregulation of the psaK gene leads to higher PPV accumulation, suggesting a role for the CI-PSI-K interaction in PPV infection.

Additional keywords: host proteins, RNA helicase, RNA silencing, sharka disease, viral proteins.

© 2006 The American Phytopathological Society