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 exploring the development and application of RNA plant virus vectors for transient expression of "foreign" proteins in plants. We have successfully engineered a tobacco mosaic virus based vector to express several animal viral antigens in plants. Our most exciting result so far has been the demonstration that foot and mouth disease viral capsid proteins expressed in plants can be used to protect experimental animals from FMDV infection. In a recent collaboration with Dr. Charles Wood, we have applied the use of plant viral vectors to express specific antigens of Human Immunodeficiency Virus (HIV-1) in plant systems. Our ultimate objective is to develop an inexpensive vaccine.

Selected Recent Publications

1. Qu, F., and Morris, T.J. Plant virus silencing suppressors and RNA silencing in plants. Invited chapter A20710, Encyclopedia of Life Sciences, Wiley, In Press, 2007.

2. Feng, Qu and Morris, T.J.,. Carmoviruses (Tombusviridae). In: B. Mahy & M van Regenmortel, Editors, Encyclopedia of Virology, Elsevier, Oxford. In Press, 2007.

3. Stenger, DC., Young, BA., Qu, F., Morris, T.J. & French, R. 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, 2007.

4. Blake, J. A., Lee, K.W., Morris, T.J. and Elthon, T.E. 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, 2007.

5. Qu, F., Ye, X., Hou, G., Sato,S., Clemente, T., and Morris T.J. RDR6 has a broad spectrum but temperature dependent antiviral defense role in Nicotiana benthamiana. J Virol., 79: 15209-15217, 2005.

6. Qu, F. and Morris, T.J. Suppressors of RNA silencing encoded by plant viruses and their role in viral infections. FEBS Lett 579, 5958-5964, 2005.

7. Ren, T., Qu, F., and Morris, T.J. Turnip crinkle virus coat protein binds to and prevents the nuclear localization of an Arabidopsis NAC transcription factor. Virology 331, 316-324, 2005.

8. Choi, C.W.,  Qu, F., Ren, T., Ye, X., and Morris, T.J. 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, 2004.

9. Pérez Filgueira, D. M., Mozgovoj, M., Wigdorovitz, A., Dus Santos, M. J., Parreño, V., Trono, K., Fernandez, F.M., Carrillo, C., Morris,  T.J. and Borca, M.V. 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, 2004.

10. D. M. Pérez Filgueira, B. P. Brayfield, S. Phiri, M.V. Borca, C. Wood & T. J. Morris. 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, 2004.

11. Qu, F., Ren, T., and Morris, T.J.. The coat protein of turnip crinkle virus suppresses posttranscriptional gene silencing at an early initiation step. J. Virol. 77: 511-522, 2003.

Education

McGill University, Montreal, Canada
B.Sc., Plant Pathology
1968

McGill University, Montreal, Canada
M.Sc., Plant Virology
1970

University of Nebraska, Lincoln, NE
PhD, Plant Virology
1973

Professional Experience

1975-76
Assistant Professor, Dept. of Biology
University of New Brunswick, Fredericton, Canada.

1976-80
Assistant Professor, Department of Plant Pathology
University of California, Berkeley, CA

1980-86
Associate Professor, Department of Plant Pathology
University of California, Berkeley, CA

1986-90
Professor, Department of Plant Pathology
University of California, Berkeley, CA

1990-2005
Director & Distinguished Professor, School of Biological Sciences
University of Nebraska, Lincoln, NE

Honors & Professional Affiliations:

Ruth Allen Award, American Phytopathological Society - 2005

Fellow - American Association for the Advancement of Science – 1997

Fellow - American Phytopathological Society - 1995

Sigma Xi Outstanding Scientist Award – 1995

Distinguished Professor - UNL College of Arts & Sciences - 1990

Editorial Board of Virology - since 198

Member - American Phytopathological Society - 1968

Member - American Society of Virology (Charter member)

Member - Society for General Microbiology

Member - American Society of Microbiology

Member - American Association for the Advancement of Science