Recent Developments in Wheat Breeding
According to data collected by the United Nations’ Food and Agriculture Organization (FAO), the food crop known as common wheat (triticum aestivum) is grown in 127 countries, producing 895 million metric tons in 2020, making it the second largest crop in volume terms behind corn (maize). The top five producing countries in that year were China, India, the Russian Federation, the United States, and Canada. Ukraine, the target of Russia’s invasion in February 2022, produced 24.9 million metric tons in that year, putting it eighth on that list. Total wheat area harvested globally has remained relatively stagnant in recent decades, having only increased by three percent in the five-year period ending in 2020 compared to the five-year period of 1961-1965.
Average global wheat yield nearly tripled over that 55-year period, from just under 12 metric tons per hectare to just under 35 tons per hectare, amounting to a 3.3 percent increase in average yield per year. The majority of that yield improvement occurred in wheat-producing nations in Asia, which realized nearly 300 percent gains in yield, largely from the adoption of higher-yielding semi-dwarf wheat varieties developed by the 1970 Nobel Prize Laureate, Dr. Norman Borlaug and increased use of nitrogen fertilizer and irrigation, while the average U.S. wheat yield increased 97 percent over the same period.
With respect to wheat trade, the five largest exporting countries in 2020 were Russia, the United States, Australia, Canada, and Ukraine. This crop is primarily an export of developed or middle income countries located in temperate latitudes in both the northern and southern hemispheres, with India the sole developing country among the top 20 exporters in that year according to FAO data.
Wheat-based products have become the staple food of choice in many urban areas of Sub-Saharan Africa, but relatively little wheat is grown within the region. In 2020, only 2.5 million tons was produced throughout the African continent, and nearly two-thirds of that was in Northern Africa countries such as Morocco and Algeria. Much of the wheat grown in Northern Africa is durum wheat (triticum durum), a different wheat species which is mainly used to produce food such as couscous and pasta. In the same year, countries in the continent imported 4.7 million tons of wheat. Some research suggests that wheat yields have plateaued in regions such as northern Europe, but that there is still room for improvement in other major wheat-producing countries such as Australia, India, and China, as well as in less developed countries in Africa and Latin America.
Although wheat is a major cereal crop grown throughout the world, the private sector has not seen fit to invest much in developing improved varieties of this crop to date. A 2001 survey of U.S. seed companies found that three-fourths of their research expenditures involved just three crops–corn, soybeans, and cotton–which not coincidentally are also the crops which account for the majority of planted acres with seeds incorporating traits created through agricultural biotechnology around the world. In 2019, these three crops accounted for 93 percent of all biotech crop acres planted globally, according to data collected by the International Service for the Acquisition of Agri-biotech Applications (ISAAA).
Most wheat breeding research takes place in the public sector–in land grant universities in the United States, in national agricultural research systems (NARS) in both developed countries like Australia and developing countries such as South Africa, and in the International Maize and Wheat Improvement Center (CIMMYT) in Mexico, which is one of the research centers of the CGIAR system. USAID’s Feed the Future initiative also funds international research into wheat genomics at Kansas State University. By the early 1990s, about 20 percent of total U.S. wheat acreage was sown with varieties with CIMMYT ancestry. Today, semi-dwarf wheat accounts for 99 percent of wheat acreage globally.
Unlike corn and soybeans, wheat with genetically modified traits has not caught on in global markets due to consumer resistance. Earlier this year, the government of Argentina approved cultivation of a new GMO wheat variety, HB4, modified for drought tolerance and resistance to the herbicide glufosinate-ammonium, within the country’s borders. The company that developed HB4, Bioceres, has already received import approval for the crop in Brazil, Australia, and New Zealand, and is currently seeking cultivation approval in the United States and Brazil. The company asserts that any crop of HB4 wheat currently in the ground in Argentina is intended for seed purposes, not for sales into food markets.
Researchers are also utilizing gene editing tools to incorporate new traits into wheat. Gene editing is different from genetic modification because it involves changes to genes already present within an organism, either shutting it down or enhancing it, as opposed to genetic modification, which typically inserts a gene from another organism into a new one. For example, Dutch and British scientists are using this technique to develop wheat varieties with reduced gluten content, to make food produced from the wheat more digestible by people suffering from celiac disease. Other gene editing work is focused on finding genes that enhance yield, the grain’s innate protein content, and resistance to specific diseases and fungi, such as fusarium blight and wheat stem rust.
Of particular interest in a widespread drought year such as the 2022/23 crop year, in which a serious drought is underway on every continent except Antartica, is development of traits to help wheat crops resist drought or extreme high temperatures. A 2019 study published in Science Advances found that a prolonged drought due to climate change could affect 60 percent of wheat-growing regions around the world by the end of the 21st century. Developing drought or heat tolerant wheat has been a major focus of research at CIMMYT over the last several years. A 2007 article published in the Agronomy Journal by a CIMMYT scientist described how recent increases in average nighttime temperatures as part of climate change has had devastating impacts on wheat yields, with every 1 degree (Celsius) increase in nighttime temperature leading to a 6 percent decline in wheat yields.
