Theodor Otto Diener

Theodor Otto Diener (28 February 1921 – 28 March 2023) was a Swiss-American plant pathologist who discovered viroids in 1971, recognized by the International Committee on Taxonomy of Viruses as a new order of subviral agents. He discovered that the potato spindle tuber disease is not caused by a virus, unexpectedly, but a short strand of RNA without protein capsid, which he termed viroid. He received the Wolf Prize in Agriculture, the highest in the field.

Biography Diener was born in Zurich, Switzerland on 28 February 1921. He served as aircraft mechanic for the Swiss Air Force in World War II He attended ETH Zurich, from which he graduated with Dr. sc. ETH degree in 1946. where on the first day, he discovered the first occurrence of a rust fungus on a cherry tree (Puccinia cerasi on the leaves) in more than 100 years.

In 1949, he emigrated to the United States, where, after a brief tenure at Rhode Island State College, he accepted a position as assistant plant pathologist at Washington State University's outlying Irrigation Experiment Station in Prosser, Washington, and that pipecolic acid causes X-disease phytoplasma symptoms.

Diener was married to Shirley Baumann and had three sons before they divorced. Diener was then married to Sybil Fox from 1968 until her death in 2012. Diener died at his home in Beltsville, Maryland on 28 March 2023 at the age of 102. Later, viroids were characterized as single stranded covalently closed circular RNA molecules occurring as highly base-paired rod-like structures. Viroids, together with viroid-like satellite RNAs have been officially endorsed by the International Committee on the Taxonomy of Viruses as a new order of subviral agents, which, in its 2014 publication, and as of 2024, encompassed Pospiviroid, Hostuviroid, Cocadviroid, Apscaviroid, Coleviroid genera of the Pospiviroidae family and Avsunviroid, Pelamoviroid, Elaviroid genera of the Avsunviroidae family.

In 1989, Diener hypothesized that the unique properties of viroids make them more plausible candidates as "living relics" of a hypothetical, precellular RNA world than are introns or other RNAs then considered as such. In 2016, Diener reevaluated his hypothesis, both reviewers agreed that Diener's hypothesis was still valid, but alternative hypotheses positing a more recent origin of viroids from cellular RNAs should also be considered.

Awards and honors 1968: Campbell Award, American Institute of Biological Sciences 1969: Superior Service Award, U.S. Department of Agriculture 1973: Fellow Award; American Phytopathological Society 1975: Alexander von Humboldt Award, Alexander von Humboldt Society 1976: Ruth Allen Award: American Phytopathological Society 1977: Elected Member; U.S. National Academy of Sciences 1978: Elected Fellow, American Academy of Arts and Sciences 1979: Elected Andrew D. White Professor-at-Large, Cornell University 1980: Elected member, Leopoldina, German Academy of Sciences 1987: Wolf Prize in Agriculture, Wolf Foundation/State of Israel 1987: National Medal of Science, USA 1988: E.C. Stakman Award, University of Minnesota 1988: Distinguished Service Award, Potomac Division, American Phytopathological Society 1989: Inducted into Science Hall of Fame, Agricultural Research Service, U.S. Department of Agriculture 1989: Named Distinguished Professor, University of Maryland, College Park, MD 1994: Named Distinguished Professor Emeritus, University of Maryland, College Park, MD