According to the U.S. Department of Agriculture, agricultural biotechnology is defined as “a range of tools, including traditional breeding techniques that alter living organisms, or parts of organisms, to make or modify products; improve plants or animals; or develop microorganisms for specific agricultural uses.”
This modern set of tools were initially brought to bear in modifying traditional row crops such as corn, soybeans, and cotton by inserting genes from other organisms to generate novel traits in those crops. This practice is commonly known as genetic engineering, and the first crop that was successfully marketed that was created using this technique was a variety of soybeans modified to tolerate the use of the pesticide glyphosate (produced by Monsanto under the name Round-up) in 1996. So-called Roundup Ready cotton was introduced to the market in 1997, and corn with this trait was first cultivated in 1998. This modification allowed farmers to use this pesticide to address weed populations in their fields without harming their primary cash crop being grown in those fields.
The other main trait that was introduced into row crops early in the biotech era was resistance to pests that had proven to be highly damaging to specific crops. This was accomplished by incorporating resistance through use of proteins designed to target specific pest species from the bacterium bacillus thuringensis (BT) into a second bacteria known as agrobacterium, which is then inserted into the crop’s genome. The first BT crop introduced was a corn variety modified to resist European corn borer, a pest which was causing severe economic harm to Midwest corn producers, in 1996.
Since the early days of genetically engineered crops, when available science was only able to incorporate a single novel trait into a crop at a time, plant breeders have learned how to develop and market crops with multiple new traits, incorporating resistance to multiple herbicides as well as multiple pests.
In addition to genetically engineered soybeans, corn, and cotton, which account for the vast majority of acres planted to such crops, there are also genetically engineered varieties of nearly 30 other crops which have been approved for cultivation, although the most recent addition to the list, genetically engineered wheat, has only been approved for cultivation in Argentina, and is undergoing field trials in a handful of other countries. This HB4 wheat is designed to be more tolerant of drought conditions than conventionally bred wheat, which should be beneficial for wheat producers as climate change continues to impact global agriculture.
The next breakthrough in agricultural biotechnology occurred in 2012, when four scientists (George Church, Jennifer Doudna, Emmanuelle Charpentier, and Feng Zhang) published work on the techniques they had developed to edit genes within a given organism to turn off or turn on certain traits. They figured out how to use guide RNA as ‘genetic scissors’ to cut DNA strands with great precision. Drs. Doudna (UC-Berkeley) and Charpentier (Max Planck Institute in Berlin) received the 2020 Nobel Prize in Chemistry for their work.
These CRISPR/CAS9 techniques have found wide applications across a range of endeavors, including medicine, but have gained strong interest in the field of agricultural biotechnology, as their use can be both more targeted and less costly and time-consuming than the earlier genetic engineering practices described above.
A 2019 article in Financial Times found that the average development and commercialization cost for a novel trait developed through genetic engineering was $130 million, as compared to about $10 million for a gene-edited trait. The former process takes about 13 years on average to complete from lab bench to market, while the latter typically takes only five years.
Through early last year, only six gene-edited crops had been approved for commercialization–in soybeans, canola, rice, maize, mushrooms, and camelina–according to an April 2022 article published in Nature Genetics.
However, a lot of other gene editing projects are already in the animal and plant breeding pipeline, and many of those efforts are focused on helping farmers adapt to the new weather stresses occurring as a result of climate change. Work aimed at developing new animal and plant varieties which are more tolerant of heat and drought has been underway for some time. For example, extensive conventional breeding work by the International Maize and Wheat Improvement Center (CIMMYT) and the International Institute of Tropical Agriculture (IITA) into developing drought tolerant maize (corn) for Africa, funded by the U.S. Agency for International Development (USAID), the Bill and Melinda Gates Foundation and other partners had resulted in the release of 160 distinct drought-tolerant maize varieties in 13 African countries by 2013, being used by an estimated 40 million smallholder farmers. In a Uganda-specific case study published in 2019, use of drought tolerant maize seed increased yield by 15 percent and reduced the probability of crop failure by 30 percent. Drought tolerant varieties of corn were introduced in the United States in 2011 (conventionally bred) and 2012 (genetically engineered), and within five years, more than one-fifth of all U.S. corn acres were planted with seed that incorporated this trait.
Research is currently underway using gene editing to try to develop drought or abiotic stress tolerance in a number of important crops, including wheat, cassava, papaya, sugar cane, and cotton. Climate change is also believed to be responsible for making plants more vulnerable to disease because many diseases are activated under stress conditions. Scientists at IITA are seeking to deactivate the gene which makes plantains (a staple crop in many African countries) vulnerable to banana streak virus. Scientists in China are also using this tool to improve the tolerance of rice crops to salinity in the soil.
A 2022 article in Plant Biology urged scientific institutions to find ways to speed up plant breeding to respond to the challenges to crop production emanating from climate change, some of which are described above. The authors suggested that “next-generation breeding approaches must integrate multidisciplinary tools, approaches, and platforms into the analytical process to accelerate the development of new climate-resilient varieties.” Clearly, use of CRISPR/CAS9 gene editing techniques will have to be part of these approaches.
