Creating a Better Leaf

Since its founding, in 2012, RIPE has expanded to include almost a hundred researchers across four continents. Long’s hope is that, in addition to the N.P.Q. and bypass tweaks, the project will come up with half a dozen other ways to “improve” photosynthesis. A team in Australia is looking at how to speed carbon dioxide’s…

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Since its founding, in 2012, RIPE has expanded to include almost a hundred researchers across four continents. Long’s hope is that, in addition to the N.P.Q. and bypass tweaks, the project will come up with half a dozen other ways to “improve” photosynthesis. A team in Australia is looking at how to speed carbon dioxide’s journey to RuBisCo, and a team in England is looking at what happens right after RuBisCo does its job. The next step would be to get these genetic modifications into globally significant crop plants—in addition to soy and potatoes, RIPE is working with corn, cowpeas, and cassava—and then into local varieties. (Farmers in different parts of the world plant different strains of corn and cassava that have been bred for local conditions.)

Long is particularly keen on getting photosynthetically souped-up seed to farmers in sub-Saharan Africa, a region that didn’t much benefit from the yield gains of the original Green Revolution. Today, more than two hundred million people there are chronically undernourished.

“If we can provide smallholder farmers in Africa with technologies that will produce more food and give them a better livelihood, that’s what really motivates the team,” Long told me. One of the Gates Foundation’s stipulations is that any breakthroughs that result from RIPE’s work be made available “at an affordable price” to companies or government agencies that supply seed to farmers in the world’s poorest countries.

Before any of RIPE’s creations could be planted in sub-Saharan Africa, though, or anywhere else, for that matter, all sorts of licenses would have to be obtained. (The gene-editing techniques that Long and his colleagues are using are themselves often patented.) Then the altered genes would have to be approved by the relevant agency in the nation in question, and the alterations would have to be bred into local varieties. So far, only a handful of African countries have O.K.’d genetically modified crops, and most of the approvals have been for G.M. cotton. A recent study noted that at least two dozen G.M. food crops—some modified for insect resistance, others for salt tolerance—have been submitted to regulatory agencies in the region but remain in limbo.

“A host of viable technologies continue to sit on the shelf, frequently due to regulatory paralysis,” the study observed. (In the U.S., practically all of the soy and corn grown is genetically modified; other approved G.M. food crops include apples, potatoes, papayas, sugar beets, and canola. In Europe, by contrast, G.M. crops are generally banned.) Meanwhile, to the extent that attitudes toward G.M. foods have been surveyed in sub-Saharan Africa, a majority of people seem to be leery of them. A recent study conducted in Zimbabwe, for example, found that almost three-quarters of the respondents believed them to be “too risky.” And smallholder farmers don’t have enough land to leave buffer zones, which means that, if they grow G.M. crops that cross-pollinate, these could mix with, or contaminate, their non-G.M. neighbors.

When I asked Long about the advisability of developing genetically modified 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 shortages come to pass,’ ” Long said. “ ‘And, if they do come to pass, it’s going to be too late to do this research.’ ”

Some 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 photosynthesis. The hack didn’t alter the steps involved in the process; instead, it added new ones. The new steps concentrated CO2 around RuBisCo, effectively eliminating the enzyme’s opportunity 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 levels 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 photosynthesis evolved independently at least forty-five times, in nineteen different plant families. (The term “C4” refers to a four-carbon compound that’s produced in one of the supplemental steps.) Nowadays, several of the world’s key crop plants are C4, including corn, millet, and sorghum, and so are several of the world’s key weeds, like crabgrass and tumbleweed.

C4 photosynthesis isn’t just more efficient 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 transformed into a C4. Like Long, Sheehy was from England, but he was working in the Philippines, at the research institute where, in the nineteen-sixties, breeders had developed the rice varieties that helped spark the Green Revolution. In 1999, Sheehy hosted a meeting 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, nearing retirement, he pulled together a second meeting on the topic. Again, the attendees were skeptical. But this time around they decided that Sheehy’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 recently, 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 reëngineering it from the chloroplast up. “Given that the C4 pathway is up to 50% more efficient than the C3 pathway, introducing 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 challenging 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 spacing is crucial to the enterprise. The C4 Rice Project involves thirty researchers in five countries. Some of the scientists are focussed on transforming the plant’s leaves, others on altering its biochemistry.

“We’re working to try to do these two things in parallel,” Langdale explained to me. “But ultimately we have to do them both.”

“I got you a gift.”
Cartoon by Avi Steinberg

The project has run into lots of obstacles; still, it has inched forward. Langdale’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 generate 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 the biochemistry,” she continued. “But I do think along the way we are going to find things that improve yield and improve efficiency, even if it’s not the full shebang.”

A few days after I spoke to Langdale, three Punjabi villagers were hit by a truck at the site of a demonstration near New Delhi. (The victims were all women in their fifties and sixties.) During the past year, hundreds of thousands of farmers in India have protested against the government of Prime Minister Narendra Modi, and for months tens of thousands have been camped out along the roads leading into the capital.

In an immediate sense, the target of the farmers’ ire is a set of laws pushed through Parliament by Modi’s party; these, they fear, could lead to an end to government price supports. In a deeper sense, though, the tensions go back to the Green Revolution. To encourage farmers to plant the higher-yielding, thirstier varieties of rice and wheat, the Indian government introduced the price-support system, in the nineteen-sixties. Now the subsidies have produced gluts of these commodities, even as growing them is depleting the country’s aquifers, and the government wants to prod farmers to move away from the crops it once prodded them to plant. To the country’s millions of farmers, most of whom own fewer than five acres, changes in the status quo seem likely to lead only to more misery.

“Many people would argue that the price supports that are currently given are barely adequate to cover the costs of production,” Sudha Narayanan, a research fellow at the International Food Policy Research Institute’s office in New Delhi, told me. But farmers depend on the supports to at least set a floor on their incomes: “They are seen as a kind of insurance.” Late last month, in a surprise move, Parliament voted to repeal the laws, but that has not put an end to the protests; farmers are now calling for an extension of price supports to other crops.

How to produce a second Green Revolution without repeating, or compounding, the mistakes of the first is a question that dogs efforts to boost yields, particularly in the Global South. With climate change, the challenges are, in many ways, even steeper than they were in the nineteen-sixties. The research institutes that helped drive the original Green Revolution, which include the International Maize and Wheat Improvement Center, in Mexico, where Norman Borlaug was stationed, and the International Rice Research Institute, in the Philippines, where John Sheehy worked, are part of a consortium called CGIAR. (The name comes from the Consultative Group on International Agricultural Research.) CGIAR is in the midst of restructuring itself.

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