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Scott Leisner Associate Professor |
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Research Interests
Our laboratory studies virus-host interactions. Viruses are serious agents of disease and it is critical to design new methods to combat these pathogens. We study plant viruses because they are useful model systems for examining host-pathogen interactions. Plants contain specific genes that provide resistance to viruses while the pathogen harbors genes that overcome this protection.
Our laboratory studies the interplay between virus and host genes influencing resistance to obtain a better picture of how plants protect themselves against disease. We are also examining the interactions between different virus genes to determine their role in the infection process.
My laboratory studies viruses, in particular plant viruses. Plant viruses are particularly good tools to study for many reasons. First, plant viruses do not infect humans so one can work with them safely. Second, many new techniques are available for studying plant viruses. Third, plant viruses are similar to animal viruses, so if we can understand how to combat plant viruses, it may be possible to apply these same techniques to inhibit animal and human viruses. Interestingly, plants use different mechanisms for combating viruses than animals do and it is unknown how most plant virus resistance functions. A major focus of my laboratory, i.e., to determine how plant virus resistance functions. We are studying resistance in three different ways:
- We are examining specific interactions between viruses and resistant host plants;
- We are examining cases where viruses antagonize each other;
- We are determining the effects of antiviral drugs against plant viruses.
Each of these areas is described in more detail below.
- Many plants prevent virus infection by way of specific resistance genes.
These genes recognize a virus and then turn on a defense response. An understanding
of how this functions is still in its infancy. We have identified two different
varieties of plants that are resistant to our virus. We have also discovered
two different viral isolates that are able to overcome resistance in each
case. We are in the process of exchanging genes between a virus that is able
to overcome a specific resistance gene with a virus that does not, to identify
the resistance-breaking gene. This will allow us to identify the viral gene
recognized by the resistance gene and to find host factors interacting with
this viral gene. In one case, we have identified the region of a viral gene
responsible for breaking resistance. We are currently analyzing this region
to identify the critical nucleotide sequence differences responsible for breaking
resistance. This type of analysis will allow us to gain a greater understanding
of how plant virus resistance works.
- Inoculation of a host with a virus often protects that host against other isolates of the same virus. This phenomenon has been observed in both animals and in plants. The plant version is called cross protection. We have discovered that inoculation with the first virus (which we call the protecting virus) prevents the spread of the second (challenge) virus through the plant. We are currently investigating how this inhibition of spread is accomplished.
- We have been testing certain antiviral drugs against our virus. The virus that we study is related to the AIDS virus and replicates itself in a similar manner. Therefore, drugs that inhibit the AIDS virus should also inhibit our virus and vice versa. This is important, not only as a tool for studying how the drugs affect a virus but it could also be used to screen potential anti-AIDS drugs in the future. Our preliminary data with this project suggest that the anti-AIDS drug, AZT, does seem to inhibit our virus.
My laboratory is also doing ecological work to study how viruses survive in nature in the absence of a host. Hence, the other major focus of my laboratory is to study virus persistence. We have recently developed a technique for isolating and detecting virus in soil. We will now be using this technique to determine the half-life of virus survival in soil as well as extending method to other types of plant viruses. This research will lead to new strategies for biological control of plant viruses.
Selected Publications
- Tang, W. and S. Leisner. Methylation of nonintegrated multiple copy DNA in plants. Biochemical and Biophysical Research Communications. 1998. 245: 403-406. Abstract
- Bobish, J.J. and S. Leisner. Novel use of polA bacteria for inserting DNA fragments into Agrobacterium binary vectors. Journal of Microbiological Methods. 1997. 31: 89-94. Abstract
- Tang, W. and Leisner, S. M. Cauliflower mosaic virus isolate NY8153 breaks resistance in Arabidopsis ecotype En-2. Phytopathology 87(8). 1997. 792-798. Abstract
- Leisner, S. M., Turgeon, R. and Howell, S. H. effects of host plant development and genetic determinants on the long-distance movement of cauliflower mosaic virus in arabidopsis. Plant Cell 5 (2). 1993. 191-202. Abstract
- Dominov, J. A. Stenzler L. Lee S. Schwarz J J. Leisner S. Howell S H. cytokinins and auxins control the expression of a gene in nicotiana-plumbaginifolia cells by feedback regulation. Plant Cell 4 (4). 1992. 451-461. Abstract
Review Articles:
- Leisner, S.M. and S.H. Howell. Long-distance movement of plant viruses. Trends Microbiol. 1993. 1: 314-317. Abstract
- Leisner, S.M. and R.Turgeon. Movement of virus and photoassimilate in the phloem: a comparative analysis. BioEssays. 1993. 15: 741-48. Abstract
Dr. Leisner's webpage
University of Toledo homepage