Daniel I. Arnon

Daniel Israel Arnon (November 14, 1910 – December 20, 1994)^[1] was a Polish-born American plant physiologist whose research led to greater insights into the operation of photosynthesis and nutrition in plants. He became Assistant Professor in 1941 and Associate Professor of cell physiology at the University of California in 1946. In 1961 he was elected to the National Academy of Sciences, in 1962 to the American Academy of Arts and Sciences, and in 1974 to the Leopoldina. The Arnon Lecture has been held annually at UC Berkeley since 2000 in early March in honour of the late Professor Daniel I. Arnon. Speakers have made significant contributions to photosynthesis or a related field and are selected by the Arnon Lecture Committee.

In the first part of his professional career, the so-called "Plant Nutrition Years (1936-1950)", Arnon and collaborators discovered the essentiality of molybdenum for the growth of all plants and of vanadium for the growth of green algae. In the second one, the so-called "Photosynthesis Period (1951-1978)", plant micronutrient work led him to photosynthesis, where in 1954 he discovered photophosphorylation. In 1973, he was awarded the National Medal of Science for "his fundamental research into the mechanism of green plant utilization of light to produce chemical energy and oxygen and for contributions to our understanding of plant nutrition."

Arnon was born on November 14, 1910, in Warsaw, to a Jewish family. Summers spent on the family's farm helped foster Arnon's interest in agriculture. His father had lost the family's food wholesale business after World War I and Arnon's readings of the works of Jack London led him to save up his money to head to California. He enrolled in the University of California, Berkeley, from Poland, and would spend his entire professional career at the school, until his retirement in 1978.^[2] He ultimately earned his Bachelor's degree in 1932 and his Ph.D. in plant physiology in 1936 at UC Berkeley under Dennis R. Hoagland. Some of his earliest research focused on growing plants in nutrient-enriched water rather than soil. Together with his supervisor he further developed the Hoagland solution which was published in modified form as Hoagland's solution (1, 2) in 1938 and revised by Arnon in 1950. During World War II, Arnon served in the United States Army in the Pacific Theater of Operations where he used his prior experience with plant nutrition on Ponape Island, where there was no arable land available, and he was able to grow food to feed the troops stationed there using gravel and nutrient-enriched water.^[3]

After returning from military service, Arnon performed research on chloroplasts and their role in the photosynthesis process. His work was able to demonstrate how energy from sunlight is used to form adenosine triphosphate, the energy transport messenger within living cells, by adding a third phosphorus group to adenosine diphosphate. In 1954, Arnon reproduced the process in a laboratory, making him the first to successfully demonstrate the chemical function of photosynthesis, producing sugar and starch from inputs of carbon dioxide and water.^[4]

A resident of Kensington, California, Arnon died at age 84 on December 20, 1994, in Berkeley, California, of complications resulting from cardiac arrest. He had three daughters and two sons. His wife, the former Lucile Soulé, died in 1986.^[3]

References[]

External links[]

• National Academy of Sciences Biographical Memoir