When Mary-Dell Chilton, then known as Mary-Dell Matchett, enrolled at the University of Illinois in the 1950s, women were discouraged from pursuing careers in science. That didn’t stop her from planning to major in physics, but falling asleep in the dull freshman lectures did. She also considered astronomy, but was told by a professor that she could not take courses on the subject until her sophomore year.
“The hell with that,” she recalled thinking, in a 2008 interview with Scientific American.
Instead, she chose chemistry. She would go on to become a pioneering figure in agricultural biotechnology, leading the research team recognized for creating the first genetically modified plant, in 1982 — a discovery that would transform global agriculture.
Dr. Chilton and her colleagues developed a method for inserting the genes of a foreign organism into a plant, which would eventually result in higher-yielding crops that resisted insects and disease and tolerated extreme weather.
At her retirement party in 2018, her son Mark Chilton later said, “I had everyone raise a glass to the astronomy professor who turned her away.”
Dr. Chilton died on June 24 at her home in Carrboro, N.C., near Chapel Hill. She was 87. The cause was congestive heart failure, Mr. Chilton said.
“She was truly driven by the thought that the world needed to have the best science could offer in order to help humanity feed itself,” Andrew Binns, an emeritus professor of biology at the University of Pennsylvania who collaborated with Dr. Chilton on developing the first genetically modified plant, said in an interview.
Among other prestigious awards, Dr. Chilton received the World Food Prize, likened to a Nobel Prize for food and agriculture, in 2013. Ten years later, she received the National Medal of Technology and Innovation.
“Millions of farmers all over the world have Dr. Chilton to thank for protecting their crops from disease, pests and climate shocks,” Tom Vilsack, the chief executive of the World Food Prize Foundation and a former U.S. secretary of agriculture, said in a tribute after her death.
Roughly 90 percent of soybeans, cotton, corn and sugar beets grown in the United States are now genetically modified. While most scientists agree that engineered foods are safe to eat, public opinion remains polarized. Questions have been raised about the long-term effects on human health and the environment; how many genetically modified crops actually address the concerns of climate change; the dangers of corporate monopolies on seed supplies; and the extent to which the promised higher crop yields have been realized.
For her part, Dr. Chilton defended genetically modified food, noting that plant engineering had been happening in nature for centuries.
“If people understood the science, I think the concern would evaporate,” she said in 2016 in an interview with the alumni association of the University of Illinois, where she received her bachelor’s degree in chemistry in 1960 and her Ph.D. in 1967.
After doing postdoctoral research in bacterial genetics at the University of Washington in Seattle, Dr. Chilton joined the faculty there in 1970, one of only two women in the department of microbiology and immunology. She worked with a soil-borne microbe called Agrobacterium tumefaciens, a kind of Uber driver for gene transport. In time, she would come to be known as the Queen of Agrobacterium.
As part of a class assignment in the mid-1970s, a student presented a paper by a Belgian scientist who proposed that Agrobacterium could insert its own DNA into a plant cell, causing plant cancer — tumor-like growths called crown gall disease. Dr. Chilton was skeptical.
“I was in it to debunk the whole story,” she said in a 2016 oral history for the Genetic Engineering and Society Center at North Carolina State University.
In the end, she was happy to prove herself wrong.
In 1977, Dr. Chilton and her collaborators published a paper in the journal Cell showing that Agrobacterium could transfer a piece of its own DNA into the cells of a tobacco plant. The DNA then merged with the plant’s chromosomes, causing the plant to produce tumors and nutrients that ensured the bacterium’s survival. It was a natural genetic engineer.
“We could scarcely believe our eyes,” Dr. Chilton wrote in 2017 in a biographical essay, “My Secret Life,” published in The Annual Review of Plant Biology.
The possibilities for manipulating plants were enticing. Dr. Chilton was 38 at the time, married with two young sons, and had no path to tenure at the University of Washington. In 1979, she and her family moved to St. Louis, where she joined the biology faculty at Washington University.
Continuing to work with Agrobacterium, she led a research team that showed it was possible to disarm the tumor-causing genes and use the bacterium to transfer foreign genes of choice into a plant cell. In 1982, her team, working with Dr. Binns of the University of Pennsylvania, transferred a yeast gene into a tobacco plant and was able to demonstrate that the gene was passed on to the plant’s descendants.
It was effectively the birth of the technology for genetically engineering plants. It paved the way for implanting genes in other crops, including corn, cotton and soybeans, to produce desirable traits — among them, resistance to pests and herbicides.
That success and similar achievements by a corporate competitor, Monsanto, and scientists from Belgium and Germany were announced at a symposium in Miami in January 1983. Dr. Chilton’s accomplishment was also acknowledged three months later in the journal Cell.
“It became pretty clear that this was going to have huge implications with crops, with agriculture,” Dr. Binns said.
Mary Dell Matchett II was born on Feb. 2, 1939, in Indianapolis and named after her mother, Mary Dell (Hayes) Matchett, who ran the household. (Her first name was hyphenated after a teacher called her Mary, which her mother disliked.) Her father, William E. Matchett, was an insurance executive.
From the age of 3 until she was a teenager, she lived mostly with her maternal grandparents in Southern Pines, N.C., because an older brother tormented her, she wrote in her autobiographical essay. Her grandmother Henrietta Dell Hayes, who owned a clothing store and kept her own books, was a formative influence on Mary-Dell, her son said, showing her “that women can do things in the world.”
She finally rejoined her immediate family, who had moved to suburban Chicago, and attended high school there. She built a telescope and, in 1956, was one of eight girls among the 40 national finalists in a prestigious Westinghouse science competition. She received a National Merit Scholarship to attend the University of Illinois.
In 1966, she married Scott Chilton, who worked as a professor of chemistry, biology and botany during his career. He died in 2004. In addition to her son Mark, she is survived by another son, Andrew, and two grandchildren.
Dr. Chilton left academia in 1983 and returned to North Carolina, helping to build the research department at what is now Syngenta, a global agribusiness and biotech company, where she worked on the genetic engineering of corn and cotton, among other projects.
She acknowledged being flattered by the praise for her achievements. “I’m an iconic character,” she jokingly told The Raleigh News & Observer in 2013.
“You can’t stop me,” she said upon being inducted into the National Inventors Hall of Fame in 2015. “When I’m after something, I work on it endlessly until I get it.”
