Genetically modified (GM) soybeans are varieties that have specific changes introduced into their DNA using genetic engineering. These modifications aim to introduce new traits, such as resistance to certain herbicides or pests, which are not naturally present. This article explores the reasons behind modifying soybeans and the scientific techniques employed.
Why Soybeans Are Genetically Modified
Soybeans are genetically modified to enhance their agricultural resilience and productivity. A primary reason is to confer herbicide tolerance, allowing soybean plants to withstand specific herbicides. This enables farmers to use broad-spectrum herbicides, such as glyphosate-based products (commercially known as Roundup), to control weeds without harming the crop. Herbicide tolerance simplifies weed management and can reduce the need for multiple applications.
Another driver for genetic modification is to provide resistance against insect pests. These traits help protect soybean plants from common agricultural threats, leading to more stable yields for farmers.
Key Techniques for Genetic Modification
Introducing new genetic material into soybean cells relies on two techniques: Agrobacterium-mediated transformation and the gene gun method. Agrobacterium-mediated transformation uses a soil bacterium, Agrobacterium tumefaciens, which transfers a segment of its DNA, known as T-DNA, into plant cells. Scientists modify this bacterium by removing its disease-causing genes and inserting desired genes, such as those for herbicide tolerance, into a Ti plasmid. The engineered Agrobacterium then delivers this beneficial DNA into the soybean plant’s genome.
The gene gun method, also known as biolistics, delivers foreign DNA directly into plant cells. This technique involves coating microscopic metal particles, typically gold or tungsten, with the desired DNA. These DNA-coated particles are then propelled at high velocity into soybean cells using a specialized device. Upon impact, the DNA detaches and integrates into the plant cell’s chromosomes.
This method was notably used in the development of the first Roundup Ready soybeans. Both Agrobacterium-mediated transformation and the gene gun effectively introduce new genetic information into soybean plants.
Developing and Testing New Varieties
After new genetic material is introduced into soybean cells, the next stage involves identifying and cultivating modified cells into whole plants. Scientists select cells that have integrated the desired genes, often by using marker genes that confer resistance to a specific antibiotic or herbicide. These selected cells regenerate into complete soybean plants through tissue culture techniques, a process that involves precise nutrient and hormone environments. The resulting plants, known as transformants, are then grown and observed.
Initial testing occurs in controlled laboratory or greenhouse settings to confirm the expression of the new trait. This involves molecular analyses to verify the presence and functioning of inserted genes, and phenotypic evaluations to observe the desired characteristic, such as herbicide tolerance. Plants demonstrating stable trait expression proceed to further evaluation.
Extensive field trials are an important subsequent step, often spanning multiple years and diverse geographical locations. These trials, typically conducted as confined field trials, assess the performance and stability of the GM soybean variety under various agricultural conditions, including different soil types, climates, and pest pressures. Researchers gather data on yield, trait efficacy, and any potential environmental interactions to ensure the variety performs as expected and remains stable. This comprehensive testing phase is essential for validating the safety and efficacy of the new GM soybean variety before commercial cultivation.