Can we engineer crops to withstand climate change?
You may not realize it, but your day revolves around plants. It’s not just mealtime: Commercial plants are used in everything from medicine to food, paper, bioplastics, textiles, rubber and a host of other products. As global climate change intensifies, though, growing many of these plants will be a major challenge.
Massive heat waves and droughts are already posing a threat to farmers: Over the next three decades, California’s San Joaquin Valley alone could lose up to 535,000 acres of arable land as a result of dwindling water supplies.
Jennifer Brophy wants to help solve that problem. She’s an assistant professor of bioengineering at Stanford, and is working on methods she hopes will be used to alter commercial plant species so they survive harsh conditions. “Climate variables are changing more rapidly than natural selection can keep up,” she says. “If we can engineer crops that are more drought tolerant, for example, maybe we can produce the same things with fewer resources.”
Brophy’s interest in sustainable engineering came early. Initially, she studied green architecture in her undergraduate years, with the intention of making buildings that make use of wind energy for cooling systems. Once she started taking architecture classes, she realized it wasn’t exactly her passion – but when she stumbled onto an article about a company that creates biofuels from bacteria, something clicked. “I thought that that was just the coolest thing. It got me really interested in pursuing bioengineering, and using it to do something with a positive social impact,” she says.
Today, Brophy is developing new genetic engineering techniques that can help plants grow in a variety of different conditions. By changing the genome of both commercial crops and soil bacteria, she thinks it may be possible to help plants survive droughts by retaining more water during a dry spell, or growing deeper roots to reach soil that hasn’t dried out yet.
In order to coax plants to respond to extreme climate, Brophy is building what she calls “genetic circuits.”In addition to changing the genes within plant cells, this method also changes how and when those genes are triggered, a bit like the logic gates inside a computer. If the plant senses a specific sugar or agrichemical, it can express one protein; if it senses another signal, it’ll express a different protein, kicking off an entirely separate chain of events. If both signals are there, the plant may be able to express something else entirely. “Using circuits, you can have plants respond in new ways to all these different inputs,” she says.
In some sense, intentionally changing a plant’s genome is an old tradition. Humans have been breeding and selecting plants based on their abilities for millennia – by choosing only seeds from the largest fruits in a harvest, we’ve collectively shaped foods like apples and tomatoes, transforming what grew naturally as tiny orbs into juicy, fist-sized domesticated foods.
For Brophy, genetic engineering is an extension of that same goal: changing a plant’s shape and function to match human needs. In this case, however, genetic circuits could allow those changes to happen on demand, rather than needing to breed them into crops gradually over generations. For farmers, that new ability would come in especially handy as weather becomes more volatile and unpredictable.
“Humans can look at a weather forecast and say, ‘it’s going to be really hot or really dry in the next couple of weeks,’ and we can plan accordingly. A plant doesn’t necessarily know what’s coming. It just knows if it’s hot or temperate right now,” she says. This can lead to problems when weather becomes erratic. A plant that usually flowers in the spring may flower in the winter if there are a few unseasonably warm days. When temperatures plummet again, the flowers die and ruin a year of crops. “It’d be great to be able to communicate with plants to tell them, ‘hey, you should wait on that flowering,’” she adds.
Controlling plants’ growth at this level is an exciting prospect, but actually putting it into practice is a long way off. At the moment, Brophy is testing the concept in the lab using a small weedy plant called Arabidopsis. She’s still early in the process of figuring out how to activate certain genes on command. While the research is in its early stages, it may help pave the way for the next generation of farming.
Brophy notes that engineering crops in the future may not just involve modifying plants – it may also involve genetically modifying soil bacteria. Instead of farmers spraying chemical signals on their crops to instigate a response, it may be possible to alter microbes that exist nearby, and program them to be tiny plant helpers. As the bacteria’s surroundings change, they could potentially send out chemical signals that tell nearby plants to shift their growth accordingly.
Plants that are submerged during flooding is one example. Once its roots are completely inundated, a plant will eventually respond – but only after those waterlogged cells deplete their existing oxygen. “It’s possible that you could use bacteria to tell the plant, ‘hey, the field flooded, you should start trying to preserve the oxygen you have,’” Brophy says. Likewise, she adds, bacteria may be able to warn the plant of approaching pathogens, like hostile fungi growing near its roots, before they attack the plant itself.
Although genetically modified plants (and to a lesser extent, bacteria) are somewhat controversial, Brophy thinks they could offer huge benefits to farmers and to society at large. Modifying non-food crops, like plants used to create textiles or biofuels, for instance, might allay some consumer concerns. In the end, though, Brophy says that dealing with climate change is going to take all the creative solutions humans can find.
“Climate change is my main motivator,” she says. “I think we need every available tool trained on this problem to ensure that we can support a growing population as the environment that we live in becomes more challenging. And hopefully, if we can make plants more robust, we’ll be able to continue growing them effectively in the future.”
