Savin Hill Park is a small oasis of trees—a splash of green located a few miles south of downtown Boston. It “gets kind of wild very fast,” says Gabriela Schlau-Cohen. And while her neighbors may not appreciate the vegetative overgrowth, Schlau-Cohen basks in it. She marvels at how plants deal with a broad range of light levels, from the searing intensity of high noon in July to the weak, meager rays of a cloudy day. This is one of the knotty questions Schlau-Cohen is working to unravel at her lab at MIT where she’s the Thomas D. and Virginia W. Cabot Career Development Professor in chemistry. And if she figures it out, it could reveal insights that would lead to higher crop yields and boosts in biofuel production.
To get at what the plants are up to, Schlau-Cohen and her students and postdocs are focusing their attention on some of the proteins responsible for photosynthesis, which operate like miniature antenna dishes for light. Schlau-Cohen fires lasers at the proteins and uses special microscopes to understand how they interact with light—how they absorb it, what happens to the light as it moves around inside the proteins, and how some of it gets converted into heat.
For instance, Schlau-Cohen discovered that one of the proteins she’s interested in has two ways of handling light—one that activates quickly in response to fast-moving clouds or shadows, and another that activates slowly during sunrise or sunset. These initial steps in photosynthesis—when sunshine first washes across a leaf—appear to have a large impact on the amount of new plant material that gets made.
“By 2050, as the population increases, it’s predicted that agricultural output won’t meet food demand,” Schlau-Cohen notes. Certain global regions, especially sub-Saharan Africa, will be hit hard by the shortfall. “To bridge that gap,” she says, “we need to figure out ways to make crops more efficient.” In other words, she hopes that knowing the details of how plants use light could allow us to engineer both crops and the algae used for biofuels to create more plant material out of the same amount of sunlight.
Schlau-Cohen also wants to know exactly how a plant moves energy inside its cells from one protein to the next. That energy can be shunted about so easily in an environment that’s “warm, wet, and noisy” is, to her, nothing short of remarkable. She uses instruments that can detect the movement of that energy in a literal flash—one quadrillionth of a second. This work could revolutionize solar power. Imagine a semi-transparent skin layered onto the windows of your home, a skin that could first absorb the sun’s energy and then shuttle it elsewhere to generate electricity.
One reason we know so little about the questions Schlau-Cohen wants to answer is that the proteins she’s after swim in membranes, and pulling a protein out of its membrane often cripples its activity. Only with the advent of the kinds of technologies Schlau-Cohen is using in her lab has it become possible to examine these proteins in their natural habitat.
One of the great ironies of Schlau-Cohen’s life is that despite her love of outdoor places like Savin Hill Park and her fierce scientific curiosity about flora, she has the opposite of a green thumb. “Every plant I keep in the house, I kill,” she confesses—even the famously hearty philodendron. She just doesn’t know how to keep them alive. And yet, if Schlau-Cohen succeeds in her lab, she’ll understand something far more tantalizing: how plants keep themselves alive.