LISA M. KRIEGER El Mercurio News
SAN JOSE, Calif. — To power a hotter, drier planet, Stanford scientists are building a smarter plant.
The team has genetically reprogrammed plants, grown in a laboratory chamber, to develop long or short, branched or thin roots, traits that change the ability to collect nutrients or water.
Controlling root growth could one day offer a powerful new tool for farmers, especially in drought- or flood-prone areas with poor soils. Over the next few decades, experts say, we will need to grow crops that can produce unprecedented abundance in increasingly harsh and unpredictable conditions as populations increase. If improved root structures can increase the yields of a food crop, perhaps more food can be put on the tables.
“The goal of all this work is to try to create plants that increase the sustainability of agriculture,” said biologist and plant systems professor José Dinneny, whose work with bioengineering professor Jennifer Brophy was published in the journal Science.
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The scientists altered root structures by introducing DNA that changes the plant’s genetic circuitry in response to environmental cues. Genetic circuits act like electrical circuits and can be turned on or off to adjust behavior.
The goal is to design plants that adapt to a specific environment or, in the future, give plants the ability to adapt.
They tested their strategy on a type of mustard called Arabidopsis thaliana because it’s a quick and easy plant to grow. Now that the researchers have shown that the idea works, they plan to apply it to commercial crops.
In the field, there may be less success. Living things respond to the wild environment in unpredictable ways. Other genes and genetic networks may require tinkering.
And critics like the Center for Food Security argue that there are better ways to solve the problem, such as improving soils or using conventional techniques to grow plants that can withstand the effects of climate change.
For years, researchers have tried to improve plants using traditional genetic engineering, introducing bits of bacterial DNA into a plant’s genome to change a specific trait, such as resistance to pests and herbicides. Corn, cotton and soybeans that are designed to survive Roundup herbicide have become standard in American fields.
But the nascent field of “synthetic biology” is accelerating research by offering more sophisticated tools. It is now possible to build or reprogram entire genomes, using gene parts made to order from foundries, or “factories,” much as industry orders cast and machined metal parts.
“The synthetic biology industry is booming in the Bay Area, with many entrepreneurs programming biological functions in living cells,” said John Cumbers, founder and CEO of SynBioBeta, a global network of biological engineers. “Now we can easily engineer an enzyme or a cell to perform a particular function, such as making a new biobased material or chemical.”
But until recently, the realm of horticulture “has largely remained off-limits to scientists,” he said. “It’s one of the holy grails of the bioengineering field: how can we program plants to grow the way we’d like them to?”
Stanford’s technique offers complex, fine-scale control, altering not just one gene but the behavior of an entire set of plant genes to induce changes in root growth under various environmental conditions.
The team built synthetic DNA that flips the circuit by creating a genetic toggle switch, like a computer logic gate, to turn genes on and off.
Genetic alternation allowed the team to adjust growth patterns, such as the number of branches in the root system, without changing the rest of the plant. For example, an “off” state created a layer of cells at the tip of a root that blocks further growth.
The team envisions programming crops to develop root systems that have more angles, so they dive deeper to find water or nitrogen, or shallower, to avoid drowning during floods from lack of oxygen. Plants could be designed for density, sending up a long taproot that doesn’t infringe on a neighbor.
Between 1960 and 2010, the “Green Revolution” boosted world food production by 175% by improving the use of fertilizers, high-yielding varieties, and irrigation techniques. But overall crop yields are stagnating.
Domestication has created plants that are inefficient consumers of water and nutrients, Dinneny said. They are designed for ideal environments.
If yields are improved, it will help preserve what is left of our nature, he added. “Unless we want to clear more forest to create more farmland,” he said, “we’re going to have to find ways to improve the way we grow plants for food.”
But the project was met with skepticism by critics such as Bill Freese, scientific director of the Center for Food Safety.
“I get the feeling that it’s very much like countless other examples of hit-and-miss, mostly miss-research, I’ve seen,” he said. “I’ve seen so many pie-in-the-sky experiences struggling due to technical hurdles.”
The promise has faded for some genetically modified plants, Freese said. For example, weeds are emerging that are resistant to Roundup herbicide, so “Roundup Ready” engineered corn and soybean brands are losing their usefulness. Farmers are now spending more on herbicides and labor costs to till the land, according to a Harvard report.
Instead of genetic fixes, we should focus on improving the environment, such as soil conditions, he said. “If you move away from genes and look more holistically at the environment the plant grows in, sometimes you can find much simpler and more straightforward solutions.”