Extension Column

Plant scientists have been employing science to improve crops for centuries. David Harris from the University of London believes that gatherers began selectively breeding wheat about 12,500 B.C. Cutting edible grasses with rock-edged sickles they took the grain-bearing grasses home. Only the strongest kernels of wheat or barley were left on the stalk because they may have been hard to cut. Those plants had stronger stalks and those plant seeds fell to the soil nearest the Neolithic campsites, and after sprouting and growing, they produced plants with maybe stronger straw and heartier kernels. Thus began an unintentional plant breeding program selecting for different and better plants.

As knowledge improved science improved. Plant scientists (Agronomists by today’s title) advanced plant varieties and traits, one gene at a time. Early plant breeders selected plant varieties that yielded better and had improved qualities for processing needs or human preferences (plants that tasted better). A striking breakthrough occurred in 1866 when an agronomist monk named Gregor Mendel crossed pea plants and became known as the “Father of Genetics.” As it turned out, traits for peas could be easily manipulated using manual cross pollination techniques. Scientists quickly adopted the discovered cross pollination strategies to create plant hybrids. These new hybrids were selected to produce plants that yielded better, produced stronger stalks and had superior quality characteristics. The new hybrids not only benefited farmers planting them (in the form of higher yields), but also consumers who noticed better and healthier food.

In 1953 scientists discovered a long molecule found in all living things they called DNA which contained genetic “codes” for traits and characteristics. Later it was discovered that desirable DNA (rust tolerance, higher yields, etc.) could be transferred to new plants with success. As a result, agronomists now found selected genes that produced positive outcomes (better yield) that could be transferred from one plant to another with greater accuracy and with less time. But plant breeding was still a “hit and miss” science. Agronomists knew which gene they wanted to advance, but needed multiple tries to finally get the desired result. This required lots of cross pollination and then further back crossing to finally achieve success. As a result, it sometimes took as many as 15 years to get a new and improved variety released.

In 1973, another scientific agronomic breakthrough was found. Plant scientists discovered how to successfully transfer a gene from one species into a completely different species. This discovery was something thought impossible by many in the scientific community and a new science was immediately born; biotechnology. Scientifically referred to as transgenic crops or Genetically Modified Organisms, this new science continues to produce better and healthier plants today.

In 1996, the first commercially available GMO crops were planted. The new GMO crop was a herbicide tolerant soybean and the herbicide applied was glyphosate. The new discovery now made controlling weeds much less difficult for producers who adopted the new technology. Herbicide tolerance in other crops followed. Glyphosate resistant corn was widely adopted by corn farmers looking for an easier method to control weeds. Another innovation occurred when an insecticide producing trait was inserted into corn plants. Known as BT corn, the trait enabled corn plants to produce a naturally occurring insecticide, eliminating chemical insecticide applications to control insects that attack corn plants. BT corn did not require farmers to apply insecticides to corn plants to control insects.

So how does transgenic technology work? Early methods used a 22 caliber pistol’s bullet that was dipped into DNA material and shot into young corn plant material. The result didn’t always work but when it did, the corn plant’s DNA accepted the foreign genes and began to replicate and multiply the new gene. From there, corn plants were tested to make sure they contained the desired traits. Current improved research uses a natural soil borne bacterium to transfer the desired trait from one species to the next.

Is GMO technology in plants safe for us to consume? It is estimated that today more than 70% of U.S. food contains GMO plants. In the U.S. prior to release into the food system GMO plants are compared to their traditional counter parts for chemical, genetic, biochemical, compositional, nutritional and environmental tests as well as known allergens. GMO crop testing is done by the FDA, EPA, and USDA. Further, more than 50 scientists from the National Academy of Science regularly evaluate GMO crops. Furthermore, countries such as Argentina, Canada, Australia and China conduct their own testing for GMO food safety. As a result, GMO crops are highly regulated and tested for both human and environmental safety.

Plant breeders also work with non-transgenic methods to transfer desirable traits from one plant to the next generation. Wheat and sunflower are two crops that are not GMO or transgenic, which means that more traditional plant breeding techniques are employed. In an effort to employ new technologies more efficiently with non-transgenic crops, plant breeders have discovered better and faster methods for transferring desirable plant traits to the next generation. DNA Marker-Assisted Selection (MAS) is one technology that is currently being employed. DNA markers have now been found that allow a plant breeder to more efficiently identify and select specific plant traits to advance to the next generation. While some genetic markers may or may not be the DNA that controls the desired trait, they act as a “flag” that point to the specific gene that plant breeders want transferred. This technology has been used since the early 2000s.

One particularly powerful form of DNA marker technology is Single Nucleotide Polymorphism or SNP (pronounced snip). This plant breeding technology allows less expensive and high-throughput DNA sequencing methods to identify and locate genes controlling important traits such as better yield and quality. SNPs located close to a particular gene act as a marker for that gene. Once the marker is identified, plant breeders know which genes to focus on and select for transfer.

Two other plant breeding methods that are currently garnering increased attention are Genomic Selection and High Throughput Phenotyping. Genomic Selection allows the breeder to use SNPs to increase the accuracy and efficiency of trait selection, with the key goal of shortening the breeding cycle time and more quickly increase the rate of genetic gain. High throughput phenotyping uses remote sensing and other technologies to rapidly and inexpensively evaluate breeding germplasm for drought tolerance, heat tolerance, plant biomass, pest tolerance, and other important production characteristics.

Further, another new plant genetic transfer technique is called Clustered Regularly Interspaced Short Palindromic Repeats or CRISPR. The CRISPR breeding method involves more nature than science and uses proteins to change the sequence and potentially “deactivate” certain undesirable genes. For instance, CRISPR technology could disable a plant’s gene that allows disease or insect susceptibility, thus making the plant resistant to specific pests, without using transgenic methods. Meaning this technology could make plants more insect or disease resistant by turning off the bad genes and enabling the good genes to thrive, without inserting foreign genes into the plant. This could also eliminate or reduce pesticide applications to control pests.

As a result of improved crop production techniques, agronomists are now able to reduce the time required to release a new and improved variety equipped with targeted pest tolerant traits from 10 years to approximately 3 years, in some cases. As a result, farmers can now employ better varieties in a third of the time it used to take to develop.

It is no accident that record crop yields are happening yearly. The record corn yield harvested in 2018 was 477 bushels per acre. In 2023, David Hula, a farmer from Charles City, Vir., set the world record for corn yield at 623 bushels per acre (bpa) in the National Corn Growers Association (NCGA) yield contest. To be sure, agricultural scientists are currently employing the best technology available and the return on investment is showing up with quicker variety release times, enhanced pest resistance, and higher yields using similar inputs.