Feeding a changing world
This story is part of our series, A Good Environment for Sustainability Research. Click here to see all stories in this collection.
As the effects of climate change surge in frequency and severity, humankind will face a slew of climate-linked threats: sea level rise, deadly heatwaves, the spread of pests and pathogens, and increased storm events, droughts, and wildfires. One alarming result of climate change that has—like many of these threats—already begun to take effect is decreased food security.
In the coming decades, crop production needs to increase in order to keep up with population growth and rising demand for biofuels, yet climate change poses many challenges for maintaining the global food supply, let alone expanding it. Farmers must cope with unstable growing seasons and shifts in the optimal growing regions for staple crops like corn and soybeans. Extreme weather events harm livestock and destroy crops, as do droughts and floods. Sea level rise erodes farmland and encroaching seawater salts the earth so that it remains unfarmable even when the water recedes. The crops that do make it to harvest, when grown under less than ideal conditions, have lower yields and are less nutritious. Key crops including wheat, rice, and soy contain lower levels of protein and other nutrients in higher atmospheric CO2 conditions.
Communities that are already vulnerable to food scarcity and malnutrition are likely to be the first and worst impacted by disruptions to their food supply, but some level of damage will be ubiquitous. Even now, extreme weather events in the United States frequently cause hundreds of millions, or even billions, of dollars in damages to agriculture.
Maintaining food security in the face of climate change is a complex, multifaceted problem of global importance, and so researchers are tackling it from many different angles. Whitehead Institute Member Mary Gehring is starting to work on ways to engineer crops that can better survive the effects of climate change and continue to produce high yields with high nutritional value. Gehring investigates epigenetics in plants, meaning she studies mechanisms that determine whether, when, and to what extent a gene is expressed, like dials turning each gene from “off” to various strengths of “on.” Epigenetic changes are heritable, and so much like variations in genes they can be passed down from cell to cell or parent to offspring, even though they don’t alter the DNA sequences themselves. Gehring is studying how to use epigenetic engineering to produce crops that can meet the food supply needs of a changing world.
“Recent research from my lab and others has shown that important aspects of seed development are controlled epigenetically, and we can manipulate the epigenome to create or select for desirable traits in plants,” Gehring says. “This could be one important approach for engineering crops to produce the yields we need in the challenging growing conditions brought about by climate change.”
Much of Gehring’s research focuses on seed development, when epigenetic modification is most dynamic, and even more particularly on the endosperm, the placenta-like tissue inside of the seed that nourishes the embryo. Endosperm is the cornerstone of our global food supply, providing two thirds of the calories that people consume in the form of rice, wheat, and other cereal grains—not to mention the feed grain for animals farmed for meat. Plant fertilization and seed development are very sensitive to temperature, so rises in global temperature due to climate change put this critical component of our food chain at risk. By deepening our understanding of seed epigenetics and determining how to use epigenetic mechanisms to control traits in the endosperm and seed at large, Gehring’s research could help develop more robust crops, protecting global food security.
No gene editing required
Gehring’s lab has demonstrated that epigenetic variation contributes to differences in seed traits in nature, and that by manipulating a plant’s epigenetic modifications, researchers can alter its seed traits. Former Gehring lab postdoc Daniela Pignatta and other lab members found that different varieties, or strains, within the same species of plant—subpopulations of a species that share distinct characteristics—likewise have distinct patterns in their epigenetic modifications. They looked at strains of the model plant Arabidopsis thaliana, which have seeds with distinct characteristics including size, and found that a small but significant number of their genes were epigenetically modified in ways that were the same within a strain but different between strains. In a later study, Pignatta, former lab technician Katherine Novitzky, and collaborators found that they could control seed traits—specifically seed size—by manipulating a seed’s epigenetic profile during its development. By altering the placement of an epigenetic chemical tag on DNA called DNA methylation, which typically silences genes, for a single gene called HDG3, the researchers could control the seed’s development and final weight. Taken together, these results show that researchers can edit the epigenome, much like they would edit the genome, to engineer plants.
In another project linking epigenetics to seed changes, Satyaki Rajavasireddy, another postdoc in Gehring’s lab, was able to rescue certain hybrid seeds that would not otherwise have reached maturity by disabling a specific DNA methylation pathway in the paternal plant. His findings could allow for the development of new hybrid plants, perhaps with favorable traits for changing climates.
The lab continues to study the roles that epigenetic mechanisms play in how seeds grow and to find links between specific epigenetic changes and valuable plant traits. This work may help us understand how to epigenetically engineer better crops more tolerant of changing environments.
“In order to both combat and adapt to climate change, we have to increase agricultural productivity while reducing agriculture’s ecological footprint,” Rajavasireddy says. “We hope that our work to understand seed development will also help us unlock novel pathways to engineer seeds with traits of interest such as increased size, increased pest tolerance or increased oil content. These kinds of advances will increase yield, and so can reduce the amount of land and nutrients required to feed a growing population.”
Roger Culos, licensed under CC BY-SA 3.0
David E. Mead
Designing crops for the future
Gehring also recently started a new line of research that focuses more directly on engineering crops. Gehring’s latest focus is on orphan crops, plants that are farmed in certain regions but that have not been widely adopted by the rest of the world. Some orphan crops are already well adapted to thrive in conditions that will become more common globally with climate change. Gehring is exploring the idea that instead of engineering global mainstay crops to be hardier, already hardy orphan crops could be engineered to be more desirable, with, for example, larger yields and more nutrients, the same way that our staple crops have been engineered from their wild forms into the versions that we know. Diversifying our staple crops would have other advantages; currently, the risk to global food security is heightened by the fact that we rely on a small set of inbred species to supply most of our demand, so that if one species becomes vulnerable to disease or pests, the impact on the global food supply could be catastrophic. The more diverse our food supply, the more resilient it should be to such threats. Gehring’s lab is beginning to study two orphan crops, pigeon pea (Cajanus cajan), a high protein plant farmed in India, Africa, and the Caribbean and false flax (Camelina sativa), an oil crop historically farmed in Europe that also has potential as a biofuel. The researchers will use a mix of genetic and epigenetic engineering to try to make the seeds bigger, more tolerant to stress, and capable of producing higher yields.
Gehring recalls that one of the formative experiences that led her to a career in plant biology was meeting Norman Borlaug, who won the Nobel Peace Prize for his contributions to the Green Revolution of the 1950s and ‘60s that used new research and technology to massively increase agricultural production worldwide, helping global food supply to keep pace with population growth.
“The work that Borlaug began is not over. When we met, he advocated for researchers to continue to revolutionize agricultural science to prepare for the next crisis in food security. That challenge is increasingly pressing, and my lab and I are eager to use the tools we have been developing to help meet it,” Gehring says.
To learn more about sustainability research at Whitehead Institute, including other projects with implications for crop yields and climate resilience, click here to listen to a podcast.
Communications and Public Affairs