48 THE SCIENTIST | the-scientist.com
PROFILESALK INSTITUTE 2019A
s a Harvard Medical School postdoc in the 1980s,
Joanne Chory tried to grow plants in the dark. Since
they can’t photosynthesize without light, the seedlings
didn’t grow very well. Most didn’t form leaves, and they didn’t
produce chlorophyll, making the sprouts white instead of green.
Not all of Chory’s plants were duds, however. Some grew as if
they were bathed in light. Because Chory was trying to under-
stand how plants respond to light, these seedlings were exactly
what she was looking for. And as it turned out, they would shape
her career trajectory and revolutionize our understanding of
plant biology.
Eager to understand how the plants grew despite living in
darkness, Chory and her colleagues analyzed the expression of
all the genes then known to be associated with light, and found
that the genes were turned off in the dark, as they are in normal
plants. Digging deeper into the plant’s genetics, the researchers
deciphered that the development of the plants that grew in
lightless conditions was driven by a mutation in a little-studied
gene that the team called de-etiolated 1, or DET1. Chory continued
to study this gene for a couple of years at Harvard and then in
her own plant genetics lab at the Salk Institute. Eventually, she
and her colleagues determined that DET1 coded for a previously
unknown receptor in the signaling pathway that determines how
plants respond to light.
This was a puzzling result, because the only light-related
receptors known to exist in plants at the time were phytochromes,
a class of photoreceptor. Many plant biologists were skeptical of
the existence of a new light receptor, Chory says. “I did my genetic
screens and went to a meeting [to present the results], and they
were all looking at me like, ‘Who are you?’” she says. She got to
work demonstrating the robustness of her research. Over the next
decade, she and her collaborators cloned DET1 and showed that
it was expressed in the plant cell’s nucleus, and that its encoded
protein (conserved in animals as well as plants) indeed played a
role in light-regulated gene expression.
Studying how plants interact with light “turned out t o be a
great research question,” says Chory. “ Yo u can have a big long
career and not even be halfway done.”LEARNING TO LOVE PLANTS
Born in Boston in 1955, Chory grew up with four brothers
and a sister. “Labs always were comfortable for me because you
had to get along in a big family, and you have to get along in a
lab too,” she says.While Chory excelled at math and science in school, she says
she didn’t know growing up that she wanted to be a scientist. A
genetics course in college sparked her interest in research, she
says. She earned a bachelor’s degree in biology from Oberlin
College in Ohio in 1977 and a PhD in microbiology from the
University of Illinois Urbana-Champaign in 1984. During
grad school, she studied the development of membranes in the
photosynthetic bacterium Rhodobacter sphaeroides in Samuel
Kaplan’s lab. Looking back, she says, studying photosynthesis may
have drawn her attention to plants, but Chory’s main goal when
searching for a postdoctoral position was to seek out a challenge,
particularly in studying the genetics of more complex organisms.
She looked at three labs studying Drosophila and three studying
plants, and ultimately chose to work with plant researcher Fred
Ausubel at Harvard Medical School.Ausubel was studying Arabidopsis thaliana, a flowering
plant also known as thale cress. It grows fast, taking as little
as six weeks to germinate and form mature seeds, and it has
a small genome of only around 135,000 base pairs. It’s also
a small plant, which made for easy cultivation in Ausubel’s
lab, located at Massachusetts General Hospital in downtown
Boston, far away from any fields. “We had to do everything
inside,” says Chory. “[Arabidopsis] was a good plant for that.”
She recalls labs with walk-in areas filled with experimental
plants, on which she and her colleagues would conduct genetic
screenings by analyzing thousands of seeds in big Petri dishes.
Within a couple of years, Chory made her seminal discovery
that mutant Arabidopsis grew in the dark.
Around the time that Chory was conducting research on
DET1 mutant plants, she met Stephen Worland in the bar of the
Cold Spring Harbor Laboratory (CSHL). Both were visiting the
research facility, and at the bar, they started chatting. Worland
was finishing his PhD at the University of California, Berkeley,
and soon afterward moved to Boston to become a postdoc at
Harvard Medical School. The two continued seeing each other,Geneticist Joanne Chory has revolutionized researchers’ understanding of how light affects plant
growth and development, and is engineering crops to combat climate change.BY EMILY MAKOWSKIInto the Light
Joanne is probably the most influential plant
biologist of the modern era.— Steven Kay, University of Southern California