Agriculture at risk: preparing the oilseed industry for a warmer world
By Rebecca Guenard
- Higher temperatures and carbon dioxide levels influence crop productivity.
- Research institutions and seed oil companies are investigating how environmental change affects crops like canola and soybean.
- The fate of agriculture is unknown, but scientists are finding solutions to ensure future global food security.
According to a world-wide economic analysis, if carbon emissions continue at their current rate, by 2100 the GDPs of all 174 countries studied will routinely suffer. A collaboration of economists from the University of Cambridge, UK; the University of Southern California, USA; the International Monetary Fund; and others, published their findings based on labor productivity data from 1960 to 2014 (https://www.nber.org/papers/w26167.pdf). They found, for example, that the United States faces a potential loss of 10.52% per year, Greece could experience a yearly loss of 12.21%, and Canada stands to lose 13.8 percent.
In a story for Olive Oil Times (https://tinyurl.com/weatherpatternsstudy), Kamiar Mohaddes, an economist at the University of Cambridge, explained that the study modeled changes in the distribution of weather patterns and deviations from average climate variables to determine their impact on productivity. “Deviations of climate variables (temperature and precipitation) from their historical norm affect labor productivity,” Mohaddes said. He says weather extremes postpone construction, interrupt supply chains, and disrupt agricultural activity.
Temperature trends from 1980 to 2008 reveal that most cropping regions and growing seasons around the world have deviated from their historical norms by more than one standard deviation, with the exception of the United States where it is less (https://doi.org/10.1104/pp.112.208298). Average temperatures, measured globally at weather stations near important crops, have increased by 0.3°C each decade. Precipitation changes are not statistically significant, but drought extent and severity in parts of the world have increased.
Climate change causes faster crop development and shorter crop duration. Increased air saturation vapor pressure from higher temperatures hampers moisture exchange between crop leaves and the atmosphere. Heat stress during reproductive periods leads to low crop yields. And a warmer, CO2-rich environment is more welcoming to pests and disease (see “Controlling insects” at the end of the article).
The world population is growing. To feed everyone living in a climate-altered future, agriculture must be as productive and nutritious as possible. There is currently no wide-spread strategy for mitigating negative environmental effects on crops, but scientists are starting to understand how crops are adapting so they can manipulate those genetic tendencies. They are identifying heat- and CO2-tolerant crops for selective planting and other tools that will help agriculture adjust to a warmer future.
Atmospheric CO2 has risen steadily since the early 1900s, increasing by 39% since the start of the Industrial Revolution. Lisa Ainsworth is a US Department of Agriculture–Agricultural Research Service (USDA–ARS) scientist with a lab at the University of Illinois, Urbana-Champaign, USA. There, she runs the free air concentration enrichment (FACE) facility, where she manipulates the atmospheric environment of plants and observes how crops respond to higher CO2.
“We can grow plants under tomorrow's atmospheric conditions but in the real world,” says Ainsworth.
As a principal source of high-quality protein and oil, soybeans were the subject of several studies over the past 20 years. Environmental effects on plant growth and seed composition. Taken as an independent variable, higher CO2 tends to be beneficial. For certain plant species, it has a fertilizing effect while also improving the plant’s water-use efficiency.
“CO2 is the substrate for photosynthesis. It is a molecule that the most abundant enzyme on the planet, RuBisCO, uses to make sugar,” says Ainsworth. “If you increase the substrate for the process of photosynthesis, then the rates of photosynthesis go up. As photosynthesis rates go up more sugars are produced and plants can grow bigger and in some cases more quickly.”
Her FACE experiments (Fig. 1) also concluded that crops lose less water through the pores in their leaves (known as transpiration) in a CO2-rich environment. Since the plant has access to plenty of CO2, the pores, called stomata, stay closed. This means the plant also retains water, demanding less of it from the soil and increasing the plant’s resistance to drought.
In 2016, Chinese researchers gathered environmental data on soybean crops and found a similar positive effect (https://doi.org/10.1021/acs.jafc.6b00008). They conducted a nation-wide study on 763 samples collected over four years from 28 soybean-producing provinces in four different regions of the country, and climate data was correlated with crop outcomes. The environmental conditions were unaltered from ambient field conditions. Overall, soybean protein and oil content increased with a higher mean daily temperature to a maximum temperature of 19.7°C. However, the results varied from region to region. For example, in areas of the country where higher protein varieties of soybean were favored for a soy-food diet, protein content decreased as temperatures rose. Like others, this study’s authors concluded that the relationship between soybean quality and the environment is complex.
“The response to interactive stresses is always complex,” says Ainsworth. In controlled experiments conducted with FACE, when they combined excess CO2 with other stresses, like high temperature or drought, the CO2 benefits disappeared. She says, when all the plants in a field take advantage of high CO2 and grow bigger, you get more biomass above ground. Bigger crops require more water, and, in a drought, these plants would not thrive.
“This was a dynamic that is not necessarily predicted because plants lower their transpiration,” says Ainsworth. “If you have more leaves in the canopy, that decrease in transpiration cannot always make up for a much bigger plant.” Bigger plants need more water, and a severe drought combined with elevated CO2 actually lowers yield, she says. A critical factor, according to Ainsworth, is temperature. More CO2 can help a plant at its optimum growth temperature, but not at very high temperatures.
Like the study in China that indicates a maximum temperature effect on soybeans, other crops have shown a similar trend. Research on fruit and vegetable crops show that the plants benefit up to a certain threshold temperature beyond which nutrients and yield suffer (https://doi.org/10.1016/B978-0-12-818732-6.00007-1).
Ainsworth is studying different genetic genotypes and how they respond to CO2 and ozone. “We are trying to identify markers that breeders can use both for ozone tolerance and CO2 response,” she says. Many scientists are combing through plant genomes hoping to uncover DNA secrets to surviving climate change.
Canola seedpods pop open prematurely in prolonged heat. The walls of the pods naturally weaken as part of the reproductive cycle, but recent research shows high temperatures accelerate the process (https://doi.org/10.1016/j.molp.2018.01.003). Oilseed yields suffer as a result since the seeds are unusable once they fall to the ground.
Lars Østergaard is a biologist at the John Innes Centre, a research institute in the UK. He was part of the team that identified the temperature effect of seed shatter, and he has pinpointed how the expression of one gene can be altered to stop it. “We knew that the INDEHISCENT (IND) gene was a key component in regulating shattering,” says Østergaard.
Researchers at University of California, San Diego first identified the importance of the IND gene using a model plant, Arabidopsis, that is related to canola. Østergaard further studied the genetic mechanisms and signaling pathways in the model and translated them into canola to determine that their function was the same. He found a way to fine tune the activity of the gene to get partial dehiscence which, he says, may be desirable for farmers of canola.
“IND is expressed very specifically in two rows of cells that run down the pod and allow separation to take place,” he says. “At higher temperatures, we saw a higher amount of gene products—mRNA and proteins—present in the specific cells where the shattering takes place.”
At low temperatures, the machinery that activates the gene cannot gain access because the DNA is bound tightly around histones (Fig. 2). As temperatures rise, the compact structure unwraps, enabling expression of the IND gene. Stopping the DNA from loosening as temperatures increase should then reduce seed shatter.
Though crucial for canola, the lessons learned in this study are not easily applicable to other crops. Most crop plants are evolutionarily different from those in canola’s Brassicaceae family, and do not possess the IND gene. Østergaard says that instead of using a model plant for more complex species, CRISPR-Cas9 can be used to study heat and CO2-tolerant genes.
Ainsworth says there are good targets within genes that could help the plant thrive in an altered climate. “Over expressing one of the enzymes in the Calvin cycle tends to increase yields under high CO2 when the temperature is well above optimal,” she says. An agriculture biotechnology company based in Woburn, Massachusetts, Yield10 Biosciences, is mining data for similar opportunities to enhance plant genetics.
“We are going to need all the technologies, and some that have not been invented yet, to sustainably feed the growing global population and improve health,” says Oliver Peoples, Yield10 Biosciences CEO. His company uses a proprietary modeling tool that searches publicly available plant genetic databases for genes with potential to improve the performance, composition, or yield of oil seed crops.
Once Yield10 has identified a gene (or genes) associated with a desirable trait, they alter the gene using biotech tools, such as traditional GMO or CRISPR, and establish a new plant line. The gene-editing techniques are first piloted in green houses and field trials using camelina. Then, the technology can be transferred into canola and soybean.
Peoples says a 2018 trial of genetically altered camelina plants resulted in an 11% increase in seed yield. Another genetically altered line produced over 25% yield. He says big seed oil companies, like Bayer, are licensing the technology to develop high-yield traits in their crops.
If anything were to happen to the food system and large-scale agriculture, we would all be in very deep trouble, he says. He hopes the recent pandemic will open consumer’s eyes to this potential tragedy and allow them to embrace advanced technology crops, not fear them. “The size of the problems are so big they need new solutions,” he says.
“We are struggling with the fact that the European Court of Justice decided that CRISPR should be regulated as GM technology. It was a serious setback for crop improvement. The technology is clearly there to address serious issues like climate change and food security,” Østergaard says.
John Purcell, head of vegetables research and development for Bayer CropScience, shares this sentiment. In a recent blog post, he indicated that it was possible to move agriculture indoors to controlled environments, but modern biology must be used to create custom germplasms conducive to vertical farming (https://www.cropscience.bayer.com).
Vertical farming involves stacking racks of plants on top of each other in an environmentally controlled building, typically with their roots submerged in a nutrient-rich solution instead of soil (Fig. 3). Some scientists believe that agriculture would be more predictable, more valuable, and more sustainable if it took place in a controlled environment.
In June, Vijai KS Shukla, the CEO of International Cosmetics Science Centre, a cosmetic ingredient supplier in Denmark, co-authored an article for Happi magazine arguing that vertical farming is particularly important for insuring a future supply of the oils and botanicals used in natural cosmetics (https://tinyurl.com/verticalfarmingoilsupply).
“The control provided by vertical farming allows us to activate the molecules of interest to create safer products for better health,” he writes.
Shukla says that many plants used in cosmetics are being illegally and unsustainably farmed, with decreasing quality. He says that through vertical farming his company can produce pure and high-quality natural products in a sustainable way. He argues that the energy consumption due to artificial light and temperature regulation on a vertical farm are on par with the energy used to sow, till, fertilize, control pests, and harvest on a conventional farm. The initial costs of the building and equipment for a vertical farm are recouped in transportation savings since the farm can be built right in the city it is serving, according to Shukla.
“Vertical farming has the potential to be another valuable tool that helps growers address future food security challenges, as well as meet changing consumer preference demands—but vertical farm operators will need improved seed genetics to maximize that potential,” says Purcell. Diseases can be controlled more effectively in a controlled environment, he says. A robust, high-throughput marker program can then be focused on finding genetic traits to improve plant architecture, time to maturity, and response to artificial light. These molecular markers would help plants grow more efficiently on a vertical farm, according to Purcell.
As they wait for these genetic discoveries to gain a stronghold, most major corporations are addressing the only climate change factor within their power, reducing greenhouse gases (GHG).
The year 2020 was a target date for many emissions cutting initiatives and, having reached their original goals, companies are back for a second round.
Ingredient supplier Archer Daniels Midland Company (ADM) of Chicago, recently announced that it plans to cut 25% of its GHG emissions by 2035, while also cutting its energy consumption by 15%. After meeting the reduction standards they set 10 years ago, the company conducted a feasibility study and determined they could do more.
“This represents an average annual reduction of 1.67% for 15 years,” says Alison Taylor, the company’s sustainability chief (https://www.foodnavigator.com).
Companies are not just cutting emissions; they now aim to adhere to limits validated by the Science Based Targets initiative (https://sciencebasedtargets.org). These targets, set by climate scientists, are meant to keep the world’s carbon budget balanced. That is the total volume of GHGs that can be emitted while maintaining temperature rise below 2o°C of preindustrial values. The Intergovernmental Panel on Climate Change (IPCC) has determined that any higher change will lead to unprecedented effects on global living conditions (https://www.foodingredientsfirst.com).
“As a leader in nutrition and agriculture, we believe the health of people is inextricably linked to the health of the planet,” says Taylor.
Olive trees have grown in the southwest region of Spain since it was part of the Roman Empire. In March, researchers from the University of Cordoba in Spain and the Research Center for Geo-Space Science (CICGE) in Portugal published an article anticipating that production will decline as the climate changes (https://doi.org/10.1016/j.scitotenv.2019.136161). Research by the USDA found that rice grown in a CO2-rich environment lost substantial amounts of protein, zinc, iron, and B vitamins per grain (https://doi.org/10.1126/sciadv.aaq1012). Over the past 60 years, northeastern Atlantic plankton populations have declined by 50%, affecting the nutritional value of commercial fish. Recent research shows that this aquatic food chain change could lead to lower omega-3 contents across the industry (https://tinyurl.com/fishnutritionalvalue).
The effect of climate change on agriculture is no longer in question. We have collected enough research to conclude that optimal growth temperature is critical to maintaining the planet’s food supply. What remains unknown is if our scientific efforts can ensure bountiful agriculture in the future.
Rebecca Guenard is the associate editor of INFORM at AOCS. She can be contacted at firstname.lastname@example.org.
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