Research Highlights

Tailoring Soybean Breeding with More Precise Gene Editing

By Barb Baylor Anderson

Soybean farmers are always on the lookout for the varieties that best match the agronomic needs of their fields. Checkoff-funded research underway at Iowa State University is exploring CRISPR-based gene editing technologies that would create optimized versions of soybean genes for breeding programs. Ultimately, that would allow soybean farmers to gain faster access to specific soybean traits that can help manage yield potential, weeds, diseases and other pests.

“CRISPR gene editing provides a new biotechnology platform that can be used to precisely change the sequences of genes in the soybean genome,” says Steve Whitham, Iowa State University plant pathologist and principal investigator on the project. Whitham is collaborating with University of Missouri plant pathologist Bing Yang. “The most exciting aspect of this technology is the precision with which changes to the DNA sequence can be made. It is much more precise than standard breeding practices and transgenic trait expression.”

Whitham says successful new approaches for CRISPR-mediated gene editing could dramatically improve the ability of soybean researchers to discover new genes and traits, accelerate novel germplasm production and broaden usefulness of CRISPR-based gene editing technologies.

For example, glyphosate resistance was originally created inserting a transgene into the soybean genome at random positions. That meant many independent random events had to be screened for the best alternative. The process was labor-intensive and expensive. With CRISPR gene editing, researchers can change the sequence of the enzyme in a soybean to become insensitive to glyphosate. Editing the gene encoding the targeted enzyme allows the plant to create resistance.

“Imagine all the ways soybeans could be improved if we could do that with any gene we know controls a trait of interest,” says Whitham. “One of our goals is to deliver the CRISPR technology in reproductive cells, which will help to simplify identification of plants that carry desirable edits that are also likely to be inherited. We seek to further optimize the system by investigating ways we can increase editing frequency occurring in reproductive cells.”

A second line of the research is related to expanding the CRISPR technology toolbox. As new technologies come online, new opportunities are created to edit genes in different ways.

One of these technologies is called base editing.

“We are currently testing two different base editors at multiple target sites in the DNA sequence. We have collected preliminary evidence that the base editors function as expected in soybeans, and now we are in the process of using the base editors to generate plants with precise edits that enable them to be resistant to the herbicides glyphosate or chlorsulfuron. These proof-of-concept experiments will set the stage for modifying genes involved in other traits,” says Whitham.

While there is no time frame for how quickly farmers will benefit from this technology, Whitham says it may be possible in the future for breeders to employ multiple CRISPR-based tools at once or in succession to make the changes needed to produce new soybean varieties.

Published: May 18, 2020