The European perspective on the genetic modification of foods generally seems like an unrelentingly negative one. While the dangers inherent to tinkering with nature are real and should be discussed, there are nonetheless a lot of appealing uses for the technology.
One significant example has to do with photosynthesis: the process whereby plants produce sugars from carbon dioxide and sunlight, generating oxygen as a by-product. Some plants use enzymes to turn CO2 into sugars composed of three carbon atoms (these are called C3 plants) while others have an enzyme (PEP Carboxylase) that allows them to produce four carbon sugars (C4 plants). The latter variety are much better at turning solar energy into sugars at temperatures above 25 degrees Celsius. The evolution of the C4 process has apparently taken place more than fifty times, in nineteen families of plant. Helping a few more important plants make the transition seems like it could be very beneficial.
C4 plants can be up to 50% more efficient than C3 ones in hot climates, while also using less water and nitrogen. Maize, a C4 plant, can yield a harvest of 12 tonnes per acre, while rice, a C3 plant, does no better than eight. If we could genetically modify rice to be a G4 plant, we could simultaneously increase crop yields, reduce the water and fertilizer needs of farmers in hot areas, and produce crops that would be less vulnerable to global warming. While there could certainly be some nasty unintended consequence of doing so, that does not seem like sufficient cause not to try.
The idea that the foods we eat now are ‘natural’ is not one that meshes very well with the fact that they have been ceaselessly modified, over thousands of years, through selective breeding. While there may be special dangers involved in mixing genes in the lab rather than out in the fields, there are also special opportunities, like the one listed above. It will be interesting to see if someone manages to pull it off.
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Another useful rice modification:
Waterproof rice can outlast the floods
“Rice grows best in flooded paddy fields. Too much water, however, and modern high-yield varieties drown within a few days. The downside of having bumper crops in good years is that the crops are vulnerable to the kind of floods that regularly trouble south and south-east Asia. More than $1 billion of rice is lost this way every year.
Now researchers have tracked down a gene in an old variety of rice largely abandoned by farmers that allows the plant to survive complete submersion. They say it could be the first lost gene of a series to be introduced into modern rice varieties to make rice more resilient to environmental hazards.”
A talk on this, for any interested Oxonians:
“Using C3 species to provide insight into the evolution of C4 photosynthesis”
Dr Julian Hibberd - University of Cambridge
Thurs 25th, 4pm, Large Lecture Theatre, Plant Sciences
Organiser: Plant Sciences
GM companies also aren’t being honest about what this technology can do—and what it can’t. In the rush to exploit the current crisis, the industry routinely promises to re-engineer crops to give massive yields—Monsanto has vowed to double grain yields by 2030—or to grow with less water or to thrive in degraded soils. But delivering on such promises will be much harder than is currently acknowledged. Whereas making corn tolerate Roundup required the manipulation of just one gene, boosting yield is vastly more complex, says Kendall Lamkey, a crop-breeding expert who chairs Iowa State University’s Department of Agronomy. Yield is the expression of a plant’s reproductive success, and reproduction takes nearly all of a plant’s survival “skills,” from its capacity to cope with temperature changes to its resistance to bugs. In other words, says Lamkey, to boost yields through genetic modification, GM companies must manipulate thousands of genes—and so far, they’ve had limited success.
Crassulacean acid metabolism, also known as CAM photosynthesis, is an elaborate carbon fixation pathway in some plants. These plants fix carbon dioxide (CO2) during the night, storing it as the four carbon acid malate. The CO2 is released during the day, where it is concentrated around the enzyme RuBisCO, increasing the efficiency of photosynthesis. The CAM pathway allows stomata to remain shut during the day; therefore it is especially common in plants adapted to arid conditions.
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The C4 pathway bears resemblance to CAM; both act to concentrate CO2 around RuBisCO, thereby increasing usefulness. CAM concentrates it in time, providing CO2 during the day, and not at night, when respiration is the dominant reaction. C4 plants, on the contrary, concentrate CO2 spatially, with a RuBisCO reaction centre in a “bundle sheath cell” being inundated with CO2.
Of rice and men
Perennial rice on the rise?
Posted by Erik Hoffner
“It was good to read this weekend in the Land Institute’s The Land Report that they’re now working hard to develop perennial rice varieties (in addition to their well-known perennial prairie polyculture experiment, which could transform large parts of the American plains back into a wildscape that produces lots of food).
Because agriculture is technically the world’s largest ecosystem, moving it toward a perennially-cropped system will have major impacts on soil health/soil building, biodiversity, energy use, and possibly carbon sequestration. “