9603168 Zook Dr. Zook is an expert in the biochemistry of plant secondary product metabolism with special focus on sesquiterpene metabolism. The importance of this pathway as the main producer of plant defense molecules has propelled the biochemical understanding of the enzymes in the pathway to the forefront of plant/pathogen interaction biochemistry. The proposal is about a well-planned antisense strategy with which defined phytoalexins, products of sesquiterpene synthesis, or the entire pathway, are eliminated by antisense technology. Additionally, synthesis will be enhanced by over-expression. The model organism is potato and the analysis of plants will include measurements at the gene expression, biochemical and physiological levels. It can be expected that the work produces fundamental knowledge about the importance or absolute essentiality of phyoalexins and will provide information of fundamental importance for our understanding of plant/pathogen interaction and how to manipulate such interaction in the future.