A flowering plant might not be able to tell how many fingers you’re holding up, but it can tell whether it’s light or dark outside and might grow differently if it suddenly finds itself in the shade of another plant.

Plants do that through photoreceptors, which are a major focus of research for John Clark Lagarias, a distinguished professor emeritus of molecular and cellular biology. 

Photoreceptors have important uses, like measuring the length of the day; plants can tell when seasons change because the days get longer or shorter. 

“Plants use that cue to decide whether they’re going to flower or leaf out as the days gets longer … or flower as fall approaches and they’re trying to beat the winter and set seed,” he said. 

Lagarias was elected to the National Academy of Sciences in 2001 and is quick to attribute much of his success to having world-class experts down the hall. But his work has major implications for the agriculture industry and beyond, and in 2017 earned him recognition from the American Society of Plant Biologists. 

In agriculture, it’s important to understand how plants respond to growing in the shade of their neighbors. Photoreceptors tell a plant whether it’s in the shade or full sun by sensing the color of light reaching the plant. Some plants respond to shade by growing faster to reach out of the shadows — a change that could divert energy farmers and breeders might prefer went to producing more seed crop.

Lagarias called that competition for full sun an “arms race” between plants.

“If you want to get more yield per acre, you want to regulate or eliminate this response,” Lagarias said. “It’s critical to understand the mechanism of that so one can interfere or bypass it, or use other means to avoid this arms race and enhance crop yield.”

A fulfilling career

Growing up in Pittsburgh, Lagarias recalled marveling at the beauty of new flowers growing out of piles of dead leaves in the woods. He went on to study botany and organic chemistry, exploring “molecules that would have a biological function” before focusing in on the structure of photoreceptors.

In 1980, fresh off a Ph.D. in chemistry at UC Berkeley, Lagarias came to UC Davis, which he called “a one-stop shop for plant biology.”

He cited UC Davis’ international recognition in agriculture and its status as a land grant university.

“I couldn’t have asked for a better institution to work and spend my career, and that’s why I’ve stayed here,” he said. “As I said to my advisor, why should I go anywhere else?”

He has continued research since transitioning to emeritus status, but has also pursued other interests, like making pottery and the recent co-founding of a startup that uses the same molecules Lagarias has studied for decades as pigments for food, industrial products and more.

“Most (artificial) food colorants are now being banned because they’re carcinogenic — they’re not something people want to eat,” Lagarias said. “The pigments I work with are natural — they’re found in plants.”

He said although it has since closed its doors, working on a startup was a fun change of pace. Lagarias said he will continue to work for as long as he continues to enjoy it. Looking back on his career as a whole, a sense of enjoyment is obvious, as he calls it “absolutely wonderful.”