Scientists Have 'Hacked Photosynthesis' In Search Of More Productive Crops
Scientists Have 'Hacked Photosynthesis' In Search Of More
Productive Crops
By DAN CHARLES January 3, 2019 4:38 PM ET Heard on
Morning Edition
There's a big molecule, a protein, inside the leaves of
most plants. It's called Rubisco, which is short for an actual chemical name
that's very long and hard to remember.
Amanda Cavanagh, a biologist and post-doctoral researcher
at the University of Illinois, calls herself a big fan of Rubisco. "It's
probably the most abundant protein in the world," she says. It's also
super-important.
Rubisco has one job. It picks up carbon dioxide from the
air, and it uses the carbon to make sugar molecules. It gets the energy to do
this from the sun. This is photosynthesis, the process by which plants use
sunlight to make food, a foundation of life on Earth. Yay for Rubisco!
"But it has what we like to call one fatal
flaw," Cavanagh continues. Unfortunately, Rubisco isn't picky enough about
what it grabs from the air. It also picks up oxygen. "When it does that,
it makes a toxic compound, so the plant has to detoxify it."
Plants have a whole complicated chemical assembly line to
carry out this detoxification, and the process uses up a lot of energy. This
means the plant has less energy for making leaves, or food for us. (There is a
family of plants, including corn and sugar cane, that developed another type of
workaround for Rubisco, and those plants are much more productive.)
Cavanagh and her colleagues in a research program called
Realizing Increased Photosynthetic Efficiency (RIPE), which is based at the
University of Illinois, have spent the last five years trying to fix Rubisco's
problem. "We're sort of hacking photosynthesis," she says.
They experimented with tobacco plants, just because
tobacco is easy to work with. They inserted some new genes into these plants,
which shut down the existing detoxification assembly line and set up a new one
that's way more efficient. And they created super tobacco plants. "They
grew faster, and they grew up to 40 percent bigger" than normal tobacco
plants, Cavanagh says. These measurements were done both in greenhouses and
open-air field plots.
The scientists now are trying to do the same thing with
plants that people actually rely on for food, like tomatoes and soybeans. They
also working with cowpeas, or black-eyed peas, "because it's a staple food
crop for a lot of farmers in sub-Saharan Africa, which is where our funders are
interested in making the biggest impact," Cavanagh says.
The funders of this project include the U.S. Department
of Agriculture and the Bill and Melinda Gates Foundation. (Disclosure: The
Gates Foundation also funds NPR.) The USDA has applied for a patent on plants
that are engineered in this way.
Cavanagh and her colleagues published their work this
week in the journal Science. Maureen Hanson, who is carrying out similar
research on photosynthesis at Cornell University, was impressed.
"This is a very important finding," she says.
"It's really the first major breakthrough showing that one can indeed
engineer photosynthesis and achieve a major increase in crop
productivity."
It will be many years, though, before any farmers plant
crops with this new version of photosynthesis. Researchers will have to find
out whether it means that a food crop like soybeans actually produces more
beans — or just more stalks and leaves.
Then they'll need to convince government regulators and
consumers that the crops are safe to grow and eat.
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