Research Interests

      We study plant viruses. My lab has pioneered studies on small RNA viruses of the Family Tombusviridae. These are some of the smallest of viruses infecting eukaryotes. We have contributed to understanding fundamental aspects of virus assembly, RNA replication and the molecular basis of virus-host interactions. Most recently, we have been exploring mechanisms of host plant resistance in Arabidopsis to turnip crinkle virus (TCV) infection. The ability to manipulate both the viral pathogen and the host plant using molecular genetic and genomic tools makes our model system particularly suitable for the study of host-pathogen interactions at the molecular level. Expression of resistance genes (R genes) is one defensive strategy employed by plants to confer resistance to specific strains of a pathogen including viruses. R genes initiate a hypersensitive type of resistance cascade (HR) that limits systemic invasion of a pathogen. Post-transcriptional silencing of the invading RNAs directed against viral pathogens has been recognized as another general defense system in plants. The recent finding that many plant viruses encode proteins that suppress this anti-viral defense system suggests that co-evolutionary adaptation between plant defense and viral counter-defense strategies is an evolutionarily active process. Recent work from our lab has shown that both types of defensive strategies are employed by plants to counteract invasion by Turnip crinkle virus (TCV), a member of the small RNA virus family, Tombusviridae. Our research has shown that specific molecular interaction between TCV coat protein (CP) and an Arabidopsis transcription factor appears to be an essential step in triggering a specific R gene based HR response. We have also shown that systemic invasion of host plants by this virus is also promoted by the viral CP functioning as a suppressor of the host RNA silencing system. Our results demonstrate that multiple functions of the viral CP ensure systemic invasion by the virus and provide important clues toward understanding the relatively sophisticated network of defense pathways that protect plants against viral infections.

      We are also involved in a collaborative research project focused on engineering soybean plants with broad spectrum resistance to viral infections using silencing pathways genes and strategies. We have also been involved in the development and application of RNA plant virus vectors for transient expression of "foreign" proteins in plants with a specific emphasis on plant production of animal and human viral antigens for use as vaccines.

Recent Publications

• Qu, F., and Morris, T.J. 2007. Plant virus silencing suppressors and RNA silencing in plants. Invited chapter A20710, Encyclopedia of Life Sciences, Wiley & Sons, pp7.
• Feng Qu and T Jack Morris. 2007. Carmoviruses (Tombusviridae). In: B. Mahy & M van Regenmortel, Editors, Encyclopedia of Virology, Elsevier, Oxford.
• Stenger, DC., Young, BA., Qu, F., Morris, TJ & French, R. 2007. Wheat streak mosaic virus lacking HC-Pro is competent to produce disease synergism in mixed infections with Maize chlorotic mottle virus. Phytopathology 97: 1213-1221.
• Blake, J. A., Lee, K.W., Morris, T.J. and Elthon, T.E. 2007. Effects of turnip crinkle virus infection on the structure and function of mitochondria and expression of stress proteins in turnips.Physiologia Plantarum 129:698-706.
• Feng Qu, Xiaohong Ye, Guichuan Hou, Shirley Sato, Thomas E. Clemente and T. Jack Morris. 2005. RDR6 has a broad spectrum but temperature dependent antiviral defense role in Nicotiana benthamiana. J Virol., 79: 15209-15217.
• Feng Qu and T. Jack Morris. 2005, Suppressors of RNA silencing encoded by plant viruses and their role in viral infections. FEBS Lett 579, 5958-5964.
• Ren, T., Qu, F., and Morris, T.J. 2005. Turnip crinkle virus coat protein binds to and prevents the nuclear localization of an Arabidopsis NAC transcription factor. Virology 331, 316-324.
• Chang Won Choi, Feng Qu, Tao Ren, Xiaohong Ye & T. Jack Morris. 2004. The RNA silencing suppressor function of Turnip crinkle virus coat protein cannot be attributed to its interaction with the Arabidopsis protein TIP. J Gen Virol 85, 3415-3420.
• D. M. Pérez Filgueira, M. Mozgovoj, A. Wigdorovitz, M. J. Dus Santos, V. Parreño, K. Trono, F.M. Fernandez, C. Carrillo, T.J. Morris & M.V. Borca . 2004. Passive Protection to Bovine Rotavirus (BRV) Infection Induced by a BRV VP8* Produced in Plants Using a TMV-based Vector. Arch Virol 149: 2337-2348.
• D. M. Pérez Filgueira, B. P. Brayfield, S. Phiri, M.V. Borca, C. Wood & T. J. Morris. 2004. Preserved antigenicity of HIV-1 p24 produced and purified in high yields from plants inoculated with a tobacco mosaic virus (TMV)-derived vector. J. Virological Methods 121, 201-208.
• Qu, F., T. Ren and T. J. Morris 2003. The coat protein of turnip crinkle virus suppresses posttranscriptional gene silencing at an early initiation step. Journal of Virology 77(1): 511-522.
• Qu, F. and T. J. Morris 2002. Efficient infection of Nicotiana benthamiana by Tomato bushy stunt virus is facilitated by the coat protein and maintained by p19 through suppression of gene silencing. Molecular Plant-Microbe Interactions 15(3): 193-202.
• Hall, J. S., R. French, T. J. Morris and D. C. Stenger 2001. Structure and temporal dynamics of populations within wheat streak mosaic virus isolates. Journal of Virology 75(21): 10231-10243.
• Hall, J. S., R. French, G. L. Hein, T. J. Morris and D. C. Stenger 2001. Three distinct mechanisms facilitate genetic isolation of sympatric wheat streak mosaic virus lineages. Virology 282(2): 230-236.
• Ren, T., F. Qu and T. J. Morris 2000. HRT gene function requires interaction between a NAC protein and viral capsid protein to confer resistance to turnip crinkle virus. Plant Cell 12(10): 1917-1925.
• Choi, I. R., D. C. Stenger, T. J. Morris and R. French 2000. A plant virus vector for systemic expression of foreign genes in cereals. Plant Journal 23(4): 547-555.
• Cohen, Y., F. Qu, A. Gisel, T. J. Morris and P. C. Zambryski 2000. Nuclear localization of turnip crinkle virus movement protein p8. Virology 273(2): 276-285.
• Robertson, N. L., R. French and T. J. Morris 2000. The open reading frame 5A of foxtail mosaic virus is expressed in vivo and is dispensable for systemic infection. Archives of Virology 145(8): 1685-1698.
• Qu, F. and T. J. Morris 2000. Cap-independent translational enhancement of turnip crinkle virus genomic and subgenomic RNAs. Journal of Virology 74(3): 1085-1093.
• Morris, T. J. 2000. Tombusviruses. In Encyclopedia of Plant Pathology, ed. O.C. Maloy & T.D. Murray, J. Wiley, N.Y.