visability of developing genetically mod-
ified varieties for use in countries that
don’t particularly seem to want them,
he told me that, at a meeting with RIPE
researchers, a similar question had been
posed to Bill Gates.
“His response was ‘Well, things might
change if these predictions of food short-
ages come to pass,’” Long said. “‘And,
if they do come to pass, it’s going to be
too late to do this research.’”
S
ome thirty million years ago, a
plant—no one knows exactly which
one, but probably it was a grass—came
up with its own hack to improve pho-
tosynthesis. The hack didn’t alter the
steps involved in the process; instead,
it added new ones. The new steps con-
centrated CO 2 around RuBisCo, ef-
fectively eliminating the enzyme’s op-
portunity to make a mistake. (To extend
the assembly-line metaphor, imagine
a worker surrounded by crateloads of
the right parts and none of the wrong
ones.) At the time, carbon-dioxide lev-
els in the atmosphere were falling—a
trend that would continue more or less
until humans figured out how to burn
fossil fuels—so even though the hack
cost the plant some energy, it offered
a net gain. In fact, it proved so useful
that other plants soon followed suit.
What’s now known as C4 photosyn-
thesis evolved independently at least
forty-five times, in nineteen different
plant families. (The term “C4” refers
to a four-carbon compound that’s pro-
duced in one of the supplemental steps.)
Nowadays, several of the world’s key
crop plants are C4, including corn, mil-
let, and sorghum, and so are several of
the world’s key weeds, like crabgrass
and tumbleweed.
C4 photosynthesis isn’t just more ef-
ficient than ordinary photosynthesis,
which is known as C3. It also requires
less water and less nitrogen, and so, in
turn, less fertilizer. About twenty-five
years ago, a plant physiologist named
John Sheehy came up with what many
other plant physiologists considered to
be an absurd idea. He decided that rice,
which is a C3 plant, should be trans-
formed into a C4. Like Long, Sheehy
was from England, but he was working
in the Philippines, at the research in-
stitute where, in the nineteen-sixties,
breeders had developed the rice varie-
ties that helped spark the Green Rev-
olution. In 1999, Sheehy hosted a meet-
ing at the institute to discuss his idea.
The general opinion of the participants
was that it was impossible.
Sheehy didn’t give up. In 2006, near-
ing retirement, he pulled together a
second meeting on the topic. Again,
the attendees were skeptical. But this
time around they decided that Shee-
hy’s scheme was at least worth a try.
Jane Langdale, a plant biologist from
Oxford, was among the researchers at
the second meeting. “There was a sense
that it was now or never,” she said re-
cently, when I spoke to her over Zoom.
“We were either going to have to get
younger people interested in this or
lose the opportunity.” Thus was born
the C4 Rice Project, which Langdale
now heads. (Sheehy died in 2019.)
The C4 Rice Project could be thought
of as RIPE’s edgier cousin. It, too, is
funded by the Gates Foundation, and
it, too, aims to feed the world by reën-
gineering it from the chloroplast up.
“Given that the C4 pathway is up to 50%
more efficient than the C3 pathway, in-
troducing C4 traits into a C3 crop would
have a dramatic impact on crop yield,”
the project’s Web site observes.
What makes the work so challeng-
ing is that C4 plants don’t just go
through extra steps in photosynthesis;
they have a different anatomy. Among
other things, the veins in the leaves of
C4 plants are much more closely packed
than those in C3 plants, and this spa-
cing is crucial to the enterprise. The
C4 Rice Project involves thirty re-
searchers in five countries. Some of the
scientists are focussed on transform-
ing the plant’s leaves, others on alter-
ing its biochemistry.
“We’re working to try to do these
two things in parallel,” Langdale ex-
plained to me. “But ultimately we have
to do them both.”
The project has run into lots of ob-
stacles; still, it has inched forward. Lang-
dale’s lab has succeeded in producing
rice plants with a greater volume of
veins in their leaves, though the volume
is still not quite high enough. Other
labs have developed rice plants that gen-
erate the crucial four-carbon compound;
these plants, however, don’t take the
next step, which is to give up one of the
carbons to be grabbed by RuBisCo.
“When we started, everybody thought
we were mad,” Langdale said. “And it
has not been an easy journey. But I think
now people look and think, You know—
they actually are making progress.
“I don’t know whether we’ll ever
make rice with the full C4 anatomy and
“I got you a gift.”
