An Historical Study of Mendelian Genetics and Virus Disease Resistance Genes
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General Audience Summary This research project in history of plant biology will bring to light some of the attempts by 20th century biologists to develop plants that are resistant to virus infection. It will also explore important connections between basic research in the lab and practical applications valued in agricultural contexts. The focus of the research will be Francis O. Holmes, a scientist at the Rockefeller Institute of Medical Research, who developed an influential paradigm for plant resistance centered on the tobacco mosaic virus. In the 1930s Holmes developed new ideas about what genetic resistance to plant viruses was and how it could be controlled in the hands of scientists. He put this work into practice by producing crop plants with genetic resistance to the tobacco mosaic virus. From his extensive laboratory and greenhouse experiments, he developed a hypothesis that wild plants and viruses co-evolved in discrete geographical locations. The investigator will determine the development and application of these ideas that continue to be used today by plant breeders to improve cultivated varieties. The findings will be integrated into undergraduate and graduate courses that explore the topics of emerging diseases, virology, virus/plant co-evolution and ecology, and broader issues of food safety. The results will be disseminated through publications, classroom and public lectures, undergraduate and graduate student training, and communication with plant scientists and historians of science, to bridge interdisciplinary boundaries. Technical Summary The focus of this research is on the development of the theory of co-evolution of host:pathogen diversity in plant pathology, with a particular concentration on knowledge production derived from tobacco mosaic virus (TMV), an intriguing object of scientific and historical study, and the experimental and theoretical work of Francis Holmes. When Holmes wrote this co-evolutionary thesis in 1951, it was strikingly innovative; it brought together Mendelian genetics as well as contemporary findings of plant evolutionary biology, virology, epidemiology, and ecology by demonstrating the plasticity of plant genomes and the role of the environment in host:pathogen interactions. This research will show how Holmes developed the practical tools and expertise to test his hypothesis that inter-species hybrids of tobacco could be used to produce TMV-resistant plants. It will also show how his experiments informed his hypothesis that the geographical center for host plants of TMV would also provide a wealth of resistance genes. Finally, it will use a hands-on approach as to how Holmes trafficked across boundaries from the lab to the field to identify and deploy resistant genes to virus infections; the focus will be on Capsicum (pepper and Tabasco), which resulted in many plant cultivars that are still in use today.