Transforming the future by making maize bioengineering more accessible

Looking around, you might not realize it, but corn is everywhere. In one form or another, it’s in the cereals in your cupboard, the cosmetics and medicines in your bathroom, the kibble in your pet’s food bowl, and the gas tank of your car. Corn, or maize, is a major crop in the United States, and its derivatives are utilized in practically every facet of our lives. Demand for it grows, even as unpredictable environmental conditions make it difficult for farmers to maintain their current yield.

For millennia, humans have intentionally bred crops to fit the ever-evolving needs of society. Nowadays, with advancements in science and technology, we can bioengineer crops by tweaking their genomes—the plants’ biological blueprints—to create drought-resistant, higher-yield, and extra-nutritious versions to fulfill our modern needs.  

However, for some crop species, including maize, bioengineering is technically challenging and requires resources unavailable at many research institutions. In work recently published in the journal In Vitro Cellular & Developmental Biology – Plant, labs from the Boyce Thompson Institute (BTI) and Iowa State University (ISU) partnered with scientists from Corteva Agriscience to establish a more accessible method for maize bioengineering that will pave the way for improving this critical crop.

Traditional bioengineering methods for maize use very small, immature embryos harvested from the corn kernels of mature plants. These embryos undergo a procedure called transformation, in which a specially designed piece of DNA is transferred to the maize genome to imbue the plants with a desired trait. For instance, a maize plant can be given a gene that boosts its resistance to a disease that could otherwise decimate a farmer’s field.

The success rate for this method of transformation depends heavily on the quality of the embryos, and high-quality embryos require advanced growing facilities. But as Dr. Joyce Van Eck, professor at BTI and one of the lead researchers on the project, divulged, “Few academic research groups have the infrastructure necessary for growing the high-quality maize required for transformation, so the method has largely been restricted to commercial industry.”

Success also depends on the type of maize, or genotype, being transformed, as each genotype has a distinct genetic makeup and variations in traits. “Many labs use the B73 genotype as a standard for experiments,” explained Dr. Ritesh Kumar, a postdoctoral researcher in the Van Eck lab and first author on the study, “but it’s very difficult to transform B73 embryos.” Thus, it has been onerous to use this maize genotype to study gene function.

These factors have all contributed to what Dr. Van Eck described as a “bottleneck” in maize research: scientists are limited in what they can accomplish by resource-intensive, non-ideal transformation techniques. Cognizant of such bottlenecks, federal organizations like the National Science Foundation (NSF) are funding research efforts to address them. Dr. Van Eck leads the Plant Bioengineering Hub within the Center for Research on Programmable Plant Systems (CROPPS), one such NSF-funded initiative that aims to revolutionize agricultural research. With CROPPS’ support, Dr. Van Eck and her fellow researchers sought to address the transformation barriers by validating a method that not only works with B73, but does so with fewer resource requirements.

To make maize transformation more accessible, the researchers adapted a technique recently developed by Corteva Agriscience scientists, in which the compact bundle of developing leaves, or leaf whorls, of young seedlings are used for transformation in lieu of embryos from mature plants. Using this method, plants only need to grow for about two weeks and do not need to reach maturity for embryo harvesting, reducing both the time involved and the need for advanced growing facilities.

This leaf whorl transformation method originally utilized a proprietary helper plasmid developed at Corteva Agriscience, which provided the molecular tools necessary for transferring the specially designed piece of DNA to the maize genome. In the current study, the researchers tested the performance of an alternative, publicly available helper plasmid developed by a group led by Dr. Kan Wang, professor in the Department of Agronomy at ISU.

Overall, the study tested the efficacy of the leaf whorl transformation method with the two different helper plasmids in two maize genotypes—PHR03 and the notoriously recalcitrant genotype B73. With the publicly available helper plasmid, the researchers reported similarly high success rates in both genotypes, demonstrating that this more accessible transformation method is effective even in resistant maize.

“It’s the first step toward making this technique more feasible for labs without greenhouse facilities, as you find in industry,” stated Dr. Van Eck. “It lowers the barriers for labs that previously couldn’t do maize transformation and, as a result, will push the field of maize research forward.”

Critical to progress in the field, and indeed to the success of this study, was the federal funding received from the NSF through CROPPS. “This study wouldn’t have been possible without NSF funds,” stressed Dr. Van Eck. “They support not only the research, but also the training of the next generation of scientists.” That next generation includes Dr. Kumar, who added that the skills he developed while working on this project will help him secure a job in academia or industry, as there is a shortage of skilled plant bioengineering researchers.

Looking forward, Dr. Kumar stated, “We are now exploring how this method will work in other maize genotypes with desirable traits, like resistance to biotic and abiotic stresses.” Although this endeavor may be more complex than they might have hoped, with adjustments needed for each genotype, it will surely advance their work and further open the floodgates for future maize genetic studies. Ultimately, the efforts of this inter-institutional team of researchers will make possible innovations and improved crops that will help not only farmers, but society at large.

Written by Alyssa Kearly

About the Boyce Thompson Institute (BTI)
Founded in 1924 and located in Ithaca, New York, BTI is at the forefront of plant science research. Our mission is to advance, communicate, and leverage pioneering discoveries in plant sciences to develop sustainable and resilient agriculture, improve food security, protect the environment, and enhance human health. As an independent nonprofit research institute affiliated with Cornell University, we are committed to inspiring and training the next generation of scientific leaders. Learn more at BTIscience.org.