The Yield of New Genetically Modified Corn Increased by 10%
Proponents of genetic engineering have long believed that it will help meet the growing global demand for food. But despite the development of many genetically modified crops that are resistant to insect pests and herbicides, scientists have struggled to boost crop yields. Now, for the first time, researchers have shown that by changing a gene that promotes plant growth, they can finally safely increase corn production by 10%, regardless of whether the growth conditions are good or bad."It's incredible." Kan Wang, a molecular biologist at Iowa State University in Ames, who was not involved in the study, said. In addition to boosting corn production, she says, the new GM technology will also inspire researchers to try to boost the production of other crops.The world's most widely grown GM crops (including soybeans, corn and cotton) have been created through a number of relatively simple genetic improvements. For example, by adding a gene from a bacterium to a specific crop species, scientists have endowed them with the ability to synthesize a protein that can kill a variety of insects. Another simple genetic manipulation can make crops resistant to glyphosate or other herbicides, and one advantage is that farmers can remove weeds without eroding the soil. There is also an operation to protect crops during drought. However, because many complex genetic factors are involved in the process of plant growth, it is difficult to develop crops that produce more food under good conditions.Starting in 2000, GM companies around the world began to carefully screen for individual genes that could improve crop yields. Yet only a handful of identified genes show promise, and many companies have reduced or stopped screening for genes involved in crop yield because of low success rates.But researchers at Corteva Agricultural Sciences, a chemical and seed company in Wilmington, Delaware, decided to study genes that act like master switches to affect crop growth and yield.The researchers selected a common class of genes called MADS-box in many plants, and then selected one of them (zmm28) to change the maize plant. The challenge in studying genes that regulate development is to ensure that they turn on the right amount at the right time and in the right tissue type. Jeff Habben, a plant physiologist at Corteva Agricultural Sciences, which led the study, said it was "easy to mess the plant up" if the genes were too active.The team's goal was to fuse zmm28 to a new promoter, a stretch of DNA that controls the timing of gene activation. After a dozen attempts, they found a reliable method.Typically, ZMM28 is initiated when maize begins to flower. While increased promoters are able to initiate ZMM28 earlier than naturally occurring, and continue to promote beneficial effects of the gene after flowering."If you make genes work harder and longer, you can make plants behave better." Wang said.The researchers tested the performance of the enhancement genes in 48 commercial corns, known as hybrid corn, which is commonly used to raise livestock. In a US corn field trial from 2014 to 2017, researchers found that the yield of GM hybrid crops was typically 3% to 5% greater than that of control crops.The team reported this week in the Proceedings of the National Academy of Sciences that some corn yields have increased by 8% to 10%. This benefit exists regardless of whether the growth conditions are good or bad."This is one of the best examples of GM crops playing a practical role in yield in the field environment." Matthew Paul, a crop scientist at the Lausanne Research Institute in Harpenden, UK, said.There are several reasons for the increase in corn yield. First, the leaves of genetically modified plants are slightly larger, which increases the plant's ability to convert sunlight into sugar by 8% to 9%."This growth is really a big deal." Plant physiologist Jingrui Wu of Corteva Agricultural Sciences says, “It is difficult to improve photosynthesis through genetic engineering.”Second, the efficiency of nitrogen utilization of these plants also increased by 16% to 18%. Nitrogen is an important soil nutrient, and complex genetic factors make it another trait that is difficult for plant breeders to control."It looks promising from a commercial point of view," said Dirk Inze, a molecular biologist at the VIB Institute in Flanders, Belgium. Corteva Agricultural Sciences has applied to the United States Department of Agriculture (USDA) for approval of new high-yielding hybrids. Although Zmm28 and its promoter occur naturally in maize, they were paired using a biotechnology regulated by USDA.Habben estimates that it will take about 6 to 10 years for the new technology to gain formal approval from countries around the world. Relevant regulatory genes are likely to increase the yield of other grains, says Inze.Large-scale field demonstrations of maize reinforce our belief that intrinsic yield can be improved if we handle it properly. It does give people inspiration, Wang said.