Last year, RIPE researchers demonstrated for the first time that it was possible to improve crop yields in the field by engineering photosynthesis. By increasing the expression levels of three genes involved in processing light, they improved tobacco yields by 20 percent.

Now the RIPE team is trying to use the same genetic-engineering trick to increase yields in more recalcitrant food crops. Making it happen in cassava falls in part to Amanda De Souza, a postdoc from Brazil.

Genetic engineering of photosynthesis in cassava is a delicate and lengthy process. De Souza opens a petri dish to show off cassava embryos, light-yellow clusters about a millimeter wide. She grows them using tissue plucked from a bud on a full-grown cassava plant. This cluster of cells, called a “callus,” can be infected with bacteria carrying the light-processing genes. Only a few cells will actually take up the genes. Those that do will then be exposed to a hormone cocktail that will drive them to grow a stem and roots.

In cassava, this genetic transformation takes eight to 10 months—that is, if everything goes well. Other key food crops, including rice and cowpeas, are a bit faster.

Down the hall, De Souza opens a closet-like room flooded with artificial sunlight. On shelves, young cassava plants are growing in plastic jars, their roots surrounded by a nutrient gel that will be picked off by hand before the plants can go into the soil.

RIPE’s experimental fields are a 10-minute drive from the labs. In this part of the country, farms mostly grow soybeans and corn. It falls to David Drag, RIPE’s field trials manager, to figure out how central Illinois’s soil can nurture crops like cassava and rice. For one project a collaborator helped him build a rice paddy. But in 2015, he recalls ruefully, he saw one of RIPE’s key projects drown in a severe late-season rainstorm, in spite of the team’s efforts to dig trenches and dams. A year’s work was lost—a humbling reminder that even the most advanced agricultural science is still at the mercy of nature.

The engineered tobacco plants in this greenhouse are paired with bags to collect the seeds they drop, for use in future tests.

Left: This robot maneuvers itself through fields to measure biomass and other aspects of plant growth.

Right: This apparatus, clamped onto a tobacco leaf, probes the plant’s metabolism. It measures temperature and humidity at the leaf’s surface and siphons oxygen and other gases emitted by the leaf into a chemical analyzer.

These young cassava plants have been genetically engineered to process sunlight more efficiently.

Left: Some of the basic research on the molecular biology of photosynthesis is done in algae in petri dishes. Right: A map of chlorophyll in a plant, made by a fluorescence imager.

Left: A fluorescence imager exposes plants to flashes of bright light to measure how quickly they respond to changing light ­levels.

Right: A view inside the fluorescence imager.