Friday, March 23 — 12:00 noon — WAG 316

Karen Scholthof (Texas A&M)

“Genes, Genetics and Evolution: F. O. Holmes and Tobacco Mosaic Virus in the Mid-20th Century”

As a practitioner-historian and plant virologist, I focus on the historiography of tobacco mosaic virus (TMV) in the early- to mid-20th century in the United States, particularly the work of Francis O. Holmes (1899-1990), a plant pathologist who spent his career at the Boyce Thompson Institute for Plant Research (1924-1932) and the Rockefeller Institute for Medical Research (1932-1960). At these private research institutions, Holmes pursued fundamental studies on TMV and developed new strategies to protect tobacco and pepper plants from the economic losses caused by plant virus infections. He determined that TMV, a virus, was a unit of heredity and incorporated Mendelian genetics and new genetic taxonomy of tobacco (Nicotiana) species to protect crops from the ravages of TMV infections. Later, taking up Vavilov’s ideas about evolutionary plant centers of genetic diversity, he developed a co-evolutionary hypothesis that wild Nicotiana plants would also be a good source for genetic resistance to TMV infection.

Holmes spent his career focusing on fundamental questions about TMV and host responses to virus infections. This differed from the more mission-oriented focus of plant pathologists at the USDA and Land Grant Colleges, who were tasked with developing rapid, practical responses to disease outbreaks in economically important agricultural crops. In contrast, I will argue, Holmes, working at the Boyce Thompson and Rockefeller Institutes, experienced a different scientific role, in which he was motivated, and permitted, to pursue fundamental laboratory research on TMV, with a longer-term promise of eventual practical benefits.


Karen Scholthof is a professor of plant pathology at Texas A&M, where she also directs the Bioenvironmental Sciences (BESC) undergraduate honors program. Her research focus is two-fold: the molecular biology of host-virus interactions in the model plant Brachypodium, and the historiography of tobacco mosaic virus in the 20th century in the United States. Karen serves as the chair of the Committee on Meetings and Programs for the History of Science Society, and is on the editorial board of the Annual Review of Phytopathology. She is an elected fellow of the American Association for the Advancement of Science (AAAS) and the American Society for Phytopathology.