Dr. Thornburg is interested in the regulation of plant defense genes. His long-term goals are to understand in molecular terms how plants respond to insect and pathogen attack. Plant responses are mediated by complex signalling pathways, signal transduction, hormones, nuclear factors and probably other unknown activities. Dr. Thornburg’s goal is to understand the biochemical mechanisms that contribute to expression of these plant defense genes.
When insects attack a plant, the plant has the ability to respond to the attack by inducing a variety of gene products following attack by insects. We have isolated and characterized several wound-inducible genes from potato that constitute part of the plant’s response to insect attack. These genes (pin2), which encode proteins termed proteinase inhibitor II, are normally quiescent in the foliage, yet, following insect attack, they are highly expressed. Our experimental goals are to understand the transcriptional activation of these genes in plant foliage. To examine this question in some molecular detail, we are using a three-pronged approach. First, we are examining the early events following wounding. Second, we are examining the early gene events which are transcriptionally activated. Third, we are taking a molecular genetic approach to identify mutatations which block wound-induction and pathogen-induction.
As an outgrowth of our work to identify mutations that block wound-induction, we have developed an interest in the metabolism of pyrimidines in plants. We have isolated cDNAs for the entire pyrimidine biosynthetic pathway, and have some of the genes isolated. Our work here is to understand the mechanisms that regulate the metabolism of this very important biosynthetic pathway in plants.