Radically Rethinking Agriculture for the 21st Century
News Feb 15, 2010
- N. V. Fedoroff, et al. Science 327, 833 (2010)
Population growth, arable land and fresh water limits, and climate change have profound implications for the ability of agriculture to meet this century's demands for food, feed, fiber, and fuel while reducing the environmental impact of their production. Success depends on the acceptance and use of contemporary molecular techniques, as well as the increasing development of farming systems that use saline water and integrate nutrient flows.
Population experts anticipate the addition of another roughly 3 billion people to the planet's population by the mid-21st century. However, the amount of arable land has not changed appreciably in more than half a century. It is unlikely to increase much in the future because we are losing it to urbanization, salinization, and desertification as fast as or faster than we are adding it (1). Water scarcity is already a critical concern in parts of the world (2).
Climate change also has important implications for agriculture. The European heat wave of 2003 killed some 30,000 to 50,000 people (3). The average temperature that summer was only about 3.5°C above the average for the last century. The 20 to 36% decrease in the yields of grains and fruits that summer drew little attention. But if the climate scientists are right, summers will be that hot on average by midcentury, and by 2090 much of the world will be experiencing summers hotter than the hottest summer now on record.
The yields of our most important food, feed, and fiber crops decline precipitously at temperatures much above 30°C (4). Among other reasons, this is because photosynthesis has a temperature optimum in the range of 20° to 25°C for our major temperate crops, and plants develop faster as temperature increases, leaving less time to accumulate the carbohydrates, fats, and proteins that constitute the bulk of fruits and grains (5). Widespread adoption of more effective and sustainable agronomic practices can help buffer crops against warmer and drier environments (6), but it will be increasingly difficult to maintain, much less increase, yields of our current major crops as temperatures rise and drylands expand (7).
Climate change will further affect agriculture as the sea level rises, submerging low-lying cropland, and as glaciers melt, causing river systems to experience shorter and more intense seasonal flows, as well as more flooding (7). Recent reports on food security emphasize the gains that can be made by bringing existing agronomic and food science technology and knowhow to people who do not yet have it (8, 9), as well as by exploring the genetic variability in our existing food crops and developing more ecologically sound farming practices (10). This requires building local educational, technical, and research capacity, food processing capability, storage capacity, and other aspects of agribusiness, as well as rural transportation and water and communications infrastructure. It also necessitates addressing the many trade, subsidy, intellectual property, and regulatory issues that interfere with trade and inhibit the use of technology.
What people are talking about today, both in the private and public research sectors, is the use and improvement of conventional and molecular breeding, as well as molecular genetic modification (GM), to adapt our existing food crops to increasing temperatures, decreased water availability in some places and flooding in others, rising salinity (8, 9), and changing pathogen and insect threats (11). Another important goal of such research is increasing crops' nitrogen uptake and use efficiency, because nitrogenous compounds in fertilizers are major contributors to waterway eutrophication and greenhouse gas emissions.
There is a critical need to get beyond popular biases against the use of agricultural biotechnology and develop forward-looking regulatory frameworks based on scientific evidence. In 2008, the most recent year for which statistics are available, GM crops were grown on almost 300 million acres in 25 countries, ofwhich 15 were developing countries (12). The world has consumed GM crops for 13 years without incident. The first few GM crops that have been grown very widely, including insect-resistant and herbicide-tolerant corn, cotton, canola, and soybeans, have increased agricultural productivity and farmers' incomes. They have also had environmental and health benefits, such as decreased use of pesticides and herbicides and increased use of no-till farming (13).
Despite the excellent safety and efficacy record of GM crops, regulatory policies remain almost as restrictive as they were when GMcrops were first introduced. In the United States, caseby- case review by at least two and sometimes three regulatory agencies (USDA, EPA, and FDA) is still commonly the rule rather than the exception. Perhaps the most detrimental effect of this complex, costly, and time-intensive regulatory apparatus is the virtual exclusion of public-sector researchers from the use of molecular methods to improve crops for farmers. As a result, there are still only a few GMcrops, primarily those for which there is a large seed market (12), and the benefits of biotechnology have not been realized for the vast majority of food crops.
What is needed is a serious reevaluation of the existing regulatory framework in the light of accumulated evidence and experience. An authoritative assessment of existing data on GM crop safety is timely and should encompass protein safety, gene stability, acute toxicity, composition, nutritional value, allergenicity, gene flow, and effects on nontarget organisms. This would establish a foundation for reducing the complexity of the regulatory process without affecting the integrity of the safety assessment. Such an evolution of the regulatory process in the United States would be a welcome precedent globally. It is also critically important to develop a public facility within the USDA with the mission of conducting the requisite safety testing of GM crops developed in the public sector.
This would make it possible for university and other public-sector researchers to use contemporary molecular knowledge and techniques to improve local crops for farmers. However, it is not at all a foregone conclusion that our current crops can be pushed to perform as well as they do now at much higher temperatures and with much less water and other agricultural inputs. It will take new approaches, new methods, newtechnology-indeed, perhaps even new crops and new agricultural systems.
In a new study in cells, University of Illinois researchers have adapted CRISPR gene-editing technology to cause the cell’s internal machinery to skip over a small portion of a gene when transcribing it into a template for protein building. This gives researchers a way not only to eliminate a mutated gene sequence, but to influence how the gene is expressed and regulated.
Researchers published today a detailed description of the complete genome of bread wheat, the world's most widely-cultivated crop. This work will pave the way for the production of wheat varieties better adapted to climate challenges, with higher yields, enhanced nutritional quality and improved sustainability.