What new knowledge did the gamma field produce?

The gamma field, along with additional equipment for irradiating plants, pollen, seeds, and other plant material, formed the basis for a years-long research program at Brookhaven. This research was part of a larger trend in the United States after WWII toward the use of radiation in biology research — a case of the available tools, and the political desire to demonstrate peaceful uses for atomic power, shaping the direction of science. The technology drove the research. As the chair of Brookhaven’s biology department wrote to new researcher Ralph Singleton in 1948, as the lab and its research program were taking shape, it would be best for Singleton to tie his research program, which would focus on maize, to radiation — perhaps Singleton could expose some seeds to x-rays as part of the experiment?

The radiation work done with plants at Brookhaven began in the late 1940s, when biologists were not yet certain that DNA was the carrier of heredity material or what the physical form of the gene actually was. Only a few years before, George Beadle and Edward Tatum had advanced their ‘one gene, one enzyme’ hypothesis, which had revolutionized genetics by showing that genes played essential and specific roles in the biochemical processes within cells. In the 1950s, scientists were still working out how genes, chromosomes and heredity were related to the basic biological processes of living cells. How and why radiation disrupted — and occasionally illuminated — these processes was not fully understood.

Brookhaven’s annual report for 1950 described the questions that would be addressed. Many different plants were being irradiated, including “maize, tomato, snapdragon, marigolds, potatoes and various varieties of weeds present in the gamma field.” Researchers wanted to address questions such as, “what is the mechanism by which chromosomes are broken by radiations?” and, “what is different with cells at one stage of division that they are more sensitive to damage than at another?” and whether there was a threshold dose of radiation under which no mutations would be produced. Concerns about nuclear fallout, past and potential, also guided the research: scientists wanted to know “how much radiation is required to produce harmful effects, either to the individual or the germ plasm.”  Corn (maize) was one of the focal points of this type of research. There were two reasons for this. One, corn was a well-known model organism — it had been used in genetic studies for decades. Two, it was an important agricultural plant, and new knowledge about its genetic material would be useful to plant breeders as well as geneticists. Researchers in 1950 were looking for mutations that had measurable effects on very specific aspects of the plant’s appearance and yield, such as “one which shortens the corn stalk, thus producing a more efficient grain-producing plant.” 

A key area of focus, in other words, was on creating and finding mutations — speeding up evolution, as these experimenters saw it, in a way that would be useful for both geneticists and agricultural plant breeders. In 1956, the lab’s annual report discussed the progress that had been made in using radiation to induce useful mutations in plants. Mutations had been found in a variety of crop plants, including wheat, oats, rice and peanuts, that made them resistant to various diseases. Mutations relating to size, cold tolerance, and other characteristics had also been found. Some research even pointed to the possibility of using “radiation to break close genetic linkages which apparently cannot be broken by any other means.” That is, they hoped to use radiation to separate genes that were very close together on the chromosome and did not separate during the shuffling process that occurs during meiosis. If this idea worked out, researchers thought that the “technique will be most useful where conventional plant breeding methods have gone as far as possible and a change is still desired in a single plant character…” Since understanding the basic mechanisms at work would lead to more effective use of the technique, “the work on this project…is being closely coordinated with the rather extensive program of basic plant genetics in progress at the Laboratory.” Brookhaven’s radiation mutation program combined theoretical genetic research with the strong possibility of immediate practical application in agriculture. 

Radiation genetics was, briefly, the hottest thing since hybrid corn. Newsweek’s coverage noted that Brookhaven corn geneticist Ralph Singleton’s “findings may well serve to advance the science of plant breeding as much as did the work of Donald Jones.” Singleton himself said that radiation genetics in agriculture “may far outshine such historic events as the development of hybrid corn.”

How historic was the development of hybrid corn? Find out here:
Hybrid Corn Revolution
The Green Revolution