Theodor Diener, Who Discovered the Tiniest of Infectious Agents, Dies at 102

Finding one thing infinitesimally tiny is rarely simple. But it is a lot tougher when the searcher would not know what to search for.

Theodor Diener, a plant pathologist at the federal Agricultural Research Service, confronted that drawback when he started investigating spindle tuber illness, an ailment that makes potatoes scrawny and misshapen.

Dr. Diener, who was 102 when he died on March 28 at his dwelling in Beltsville, Md., labored for years to search out the wrongdoer, leading to the discovery of the smallest recognized infectious agent, which he named a viroid.

Spindle tuber illness, which was first recognized in the Twenties, generally causes disastrous penalties for crops. Studies present that the ailment can decrease potato crop yields by as much as 64 p.c; solely strict quarantine, and in some instances destruction of complete crops, can include this extremely contagious sickness. But even a long time after the illness was recognized, scientists have been nonetheless undecided what brought on it.

Dr. Diener and colleagues like William B. Raymer at the analysis service, half of the Department of Agriculture, spent most of the Sixties attempting to unravel the puzzle.

They studied the pathogen in tomato crops, which they discovered had a far shorter incubation interval for tuber spindle illness than potatoes, and used cutting-edge strategies to determine that this infectious agent contained no proteins and that RNA, or ribonucleic acid, one of the constructing blocks of life, was essential to it.

Dr. Raymer left the analysis service for a job in non-public business in 1966, and Dr. Diener “spent the subsequent 5 years isolating and characterizing the viroid, verifying his experiments, filling in the holes” and “getting ready to fulfill the skepticism that usually greets proposals of new, ‘unattainable’ ideas,” in keeping with a 1989 article in Agricultural Research. journal titled “Tracking the Elusive Viroid.”

(*102*) that point, scientists thought that one thing as small as viroids, that are one-eighth the measurement of many viruses, have been too minuscule to trigger an an infection.

Like viruses, viroids reproduce by invading wholesome cells and reprogramming them to duplicate the viroid’s genetic make-up as a substitute of the cell’s personal.

But viruses, which will be made of DNA or RNA, have a protecting coat made of proteins and encode proteins as soon as they’ve invaded cells. Viroids, against this, are made solely of RNA, don’t have the protein coat and don’t encode proteins.

“Its technique of producing illness is mainly completely different from that of all different viruses,” Dr. Diener mentioned at a global assembly of virologists in 1972.

After figuring out the viroid that brought on spindle tuber illness, he helped develop a take a look at to detect it. He went on to obtain the National Medal of Science from President Ronald Reagan in a Rose Garden ceremony at the White House in 1987.

William Haseltine, a virologist and former professor at Harvard Medical School who has written a sequence of articles about viroids for Forbes journal this yr, mentioned in a cellphone interview that Dr. Diener “found an entire new department of life, in all probability the most elementary department of life, at least to my definition.”

Dr. Diener’s discovery has implications for scientific understanding of the origins of life and for drugs, contributing to breakthroughs like the use of messenger RNA to develop vaccines for Covid-19, Dr. Haseltine mentioned.

Since Dr. Diener’s discovery, scientists have recognized greater than 30 completely different viroids that trigger illnesses in crops, like the avocado sunblotch, coconut cadang-cadang, pear blister canker and hop latent viroids, which will be devastating to hemp and hashish crops.

Theodor Otto Diener was born on Feb. 28, 1921, in Zurich, the solely youngster of Theodor and Hedwig (Baumann) Diener. His father was a postal employee, his mom an accountant.

As a toddler he was fascinated with animals and saved a colony of mice, a turtle and a canary, a lot to his dad and mom’ discomfort. His father, he wrote in a self-published memoir, “Of Humans, Humanoids, and Viroids” (2014), didn’t admire his consuming curiosity in “small dwelling issues.”

He “typically shook his head in disbelief after I was enthusiastically holding forth — describing attributes of some tiny insect, worm or fungus,” Dr. Diener wrote.

Dr. Diener did airplane upkeep for the Swiss Air Force throughout World War II, and in 1948 he accomplished his doctorate in biology at the Swiss Federal Institute of Technology.

He emigrated to the United States in 1949 and, after a short time in New York City, moved to Spokane, Wash., for a job at the University of Washington. He moved to Maryland to work with the authorities analysis service 10 years later.

Dr. Diener’s first marriage, to Shirley Baumann, resulted in divorce. In 1968 he married Sybil Fox, who died in 2012.

He is survived by three sons from his first marriage, Michael, who confirmed the dying, Theodore and Robert; 5 grandchildren; and three great-grandchildren.

Dr. Diener’s different honors embody his election to the National Academy of Sciences and to the American Academy of Arts and Sciences. In 1987, he obtained the Wolf Prize in agriculture, a $100,000 award given by the Wolf Foundation in Israel.

Viroids could also be far more than agricultural pests. Research means that they existed at the earliest levels of life on Earth, unnoticed till Dr. Diener took up the search.

Dr. David A. Relman, a microbiologist at Stanford University, wrote of Dr. Diener in an e-mail, “His discovery of viroids and their function in plant illnesses helped to disclose the function of RNA molecules in fundamental organic processes, and probably in the origin of life itself.”

Ashley Shannon Wu contributed reporting.

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