As the human population continues to expand, agriculture increasingly is pressed to meet the burgeoning demand for food. Meanwhile, urbanization is shrinking farmland and encroaching on wildlands, limiting the amount of available crop area. The result is a need for more agricultural productivity in a way that minimizes environmental impact.

According to Blake Meyers, who delivered the 2023 Jefferson Lecture at Mitchell Hall on the University of Delaware’s Newark campus last month, one way to accomplish this is by optimizing and, in some cases, redesigning plants and their architecture. From a genetic perspective, this could include altering which genes get turned on and which genes get turned off, either through traditional breeding or biotechnology approaches. 

It’s an area in which Meyers is making pioneering contributions. A leading plant biologist at the Donald Danforth Plant Science Center in St. Louis and a former member of the UD faculty, Meyers developed or co-developed several critical methodologies and applications of gene sequencing technologies that have advanced our understanding of plant biology. In early work with Pam Green at UD, he and his team were the first to use next-generation sequencing to analyze small RNAs. Today, Meyers believes that small RNAs, minuscule molecules of ribonucleic acids with the ability to silence genes, are a key part of the toolkit for crop improvement. 

Much of Meyers’ work in the last decade has focused on reproductive biology, understanding how pollen develops in the anthers of corn (maize). Meyers credited UD’s Jeff Caplan, professor and director of the Bio-Imaging Center, with providing critical, detailed imaging of the corn reproductive layers in action, allowing them to spatially map the activity for focused study. They worked with collaborators to sequence the small RNAs across the developmental timeline, measured by anther size. They saw a tremendous burst of small RNA production early in anther development and a second burst of production coincident with meiosis, a process of cell division required for reproduction. Further, there are genes that are active only at those moments with the sole purpose of producing these small RNAs. 

While much of what these small RNAs do remains unknown, researchers do know that they are essential for plant male reproductive success. If these reproductive small RNAs are shut off, it leads to male sterility. Practical application of this knowledge includes seed production, which is of huge importance to the U.S. economy. This is particularly true as it relates to hybridization, a major focus for the agricultural industry.

Hybrid crops have become a popular way to help farmers boost productivity over the last 40-50 years, said Meyers. By crossing different varieties, mainly of corn, the resulting hybrid seeds and thus the progeny that grow from the seeds are more robust than either of the parents, with the ability to deliver increased yields over other varieties. This ‘hybrid vigor’ was discovered in the 1930s and led to the production of commercial hybrid corn varieties.

“Our interest in reproductive biology is whether we can use that knowledge to implement processes for making hybrid crops in species where a good cross-hybridization system is not currently available, like wheat or barley. Those are our biggest targets,” said Meyers. 

His lab and other research groups are also working on ways to use small RNAs to improve plant architecture, for example, by adapting crop plants to better withstand stress or for higher performance in an agricultural system. 

“A non-optimized plant might sprawl, fall over when the wind is strong, and not survive well under wet conditions,” said Meyers. “But if you can reduce the stature and make it more upright, more compact so it doesn't fall over when the wind blows, and make it more resilient to common challenges, then you can increase the density of your plants, and the increased density may boost yields.” 

In other work, Meyers’ team showed that some mutations that cause male sterility display a conditional response that can be reversed by changing the environmental conditions. This creates an opportunity for hybrid seed production. For example, under cool conditions the researchers found that certain male-sterile corn mutants become fertile. By altering growth conditions, the lines can alternatively be self-fertilized for production in larger numbers or forced to hybridize to produce higher-yielding varieties. Practically, Meyers called it an environmental “switch” that rice breeders have used for many decades to enhance crop development and agricultural production. Adapted to other cereal crops, Meyers said there is potential to increase agricultural production in new areas. 

“We think the process of hybrid seed production using this phenomena we’ve discovered in maize and wheat has practical applications for the production of hybrid seed,” he said. 

Inspiring tomorrow’s scientific leaders

Prior to delivering the Jefferson Lecture, Meyers shared his career experience with graduate students over lunch. The discussion covered a wide range of topics, from Meyers’ work at the Danforth Plant Science Center to his passion for mentoring students to artificial intelligence, machine learning, bioinformatics and plant biology. In the end, though, conversation wound back to the importance of small RNAs across different research areas.

“We’ve come a long way, but there are still intriguing biological pathways in which we have a poor understanding of how these small RNAs function,” said Meyers, who was inducted into the National Academy of Sciences in 2022.

The fun of biology, Meyers added, is that there are many interesting questions that have yet to be formulated or explored. It’s a truth that spoke to Carolyn Remsburg, a recently hooded doctoral graduate who earned her doctorate in molecular biology. Remsburg spent over a decade as a practicing veterinarian before deciding to return to higher education. Under the advisement of Jia Song, UD associate professor of biological sciences, she has spent the last several years studying sea urchin embryos to understand the role of microRNAs in gene regulation in early development.

“As a veterinarian, you apply science, but you aren’t doing science every day. I wanted to do basic science,” said Remsburg, who plans to continue studying these basic processes in C. elegans as a postdoctoral researcher with Aimee Jaramillo-Lambert, assistant professor of biological sciences at UD.

Other graduate students in attendance included Guna Gurazada, an engineering doctoral student studying bioinformatics data science, Noah Totsline, a master’s student in plant science, and Deji Adekanye, a biological sciences doctoral student.

About the Edward G. Jefferson Lecture

Endowed by a gift from the Unidel Foundation, the Edward G. Jefferson Lecture is named in honor of the late chairman and chief executive officer of the DuPont Co., UD trustee emeritus and UD benefactor. The lecture highlights distinguished work in the life sciences.