Jeffrey Caplan (left), UD associate professor of plant and soil sciences, and post-doctoral researcher Kun Huang, are part of a $3.5 million NSF grant to understand how pollen develops in plants, such as corn.

Food security under changing climate

UD part of $3.5 million NSF-funded study to improve key crop resilience

Jeffrey Caplan (left), UD associate professor of plant and soil sciences, and post-doctoral researcher Kun Huang, are part of a $3.5 million NSF grant to understand how pollen develops in plants, such as corn.
Jeffrey Caplan (left), UD associate professor of plant and soil sciences, and post-doctoral researcher Kun Huang, are part of a $3.5 million NSF grant to understand how pollen develops in plants, such as corn.

An interdisciplinary team of researchers from the University of Delaware, the Donald Danforth Plant Science Center and Stanford University have been awarded a four-year, $3.5 million National Science Foundation grant to address concerns about reduced harvests of corn and other cereal grasses.

The project will focus on understanding the small ribonucleic acid (RNA) pathways involved in anther development and crop development when plants are challenged by adverse environmental conditions. Small RNAs are tiny messengers that carry genetic information inside living cells, in this case anthers—the site of pollen development in plants.

According to the Environmental Protection Agency, grains such as wheat, corn and rice grown in the United States account for roughly 25 percent of all grains worldwide. Changes to climate, including the frequency and intensity of extreme weather, are expected to impact crop yields at a time when the planet’s population — and the demand for food — is rising.

The collaborative effort brings together expertise in plant genomics and targeted genetic changes; cutting-edge imaging techniques; and bioinformatics, the science of collecting and analyzing complex biological data, with a focus on developmental biology to meet the demands of producing more nutritious food in climates with higher temperatures.

Jeffrey Caplan, UD associate professor of plant and soil sciences in the College of Agriculture and Natural Resources, is a co-principal investigator on the project, which is led by Blake Meyers, a member of the Donald Danforth Plant Science Center and professor in the University of Missouri’s Division of Plant Sciences. The work is a continuation of a previous NSF study Meyers began while chair of UD’s Department of Plant and Soil Sciences.

Caplan and his collaborators will investigate the life cycle and functions of a class of RNAs that support anther development in grass flowers, which are flowers that are pollinated by wind, eliminating the need for eye-catching petals to attract insects. Anthers are critical in the reproduction of flowering plants because they are the site of pollen development and contain the sperm cells necessary for reproduction. In corn, also known as maize, anthers are located on the whispy tassels found at the top of the cornstalk. Prior research has demonstrated that anther development will often stall or fail under high temperatures, leaving the plants sterile or with reduced fertility, thus decreasing the harvest.

Backstory on corn

Anthers are particularly important to the production of hybrid corn seed. Hybrid corn seed differs from naturally pollinated corn seed in that it is produced by cross-pollinating plants and its use has contributed to increases in agricultural production in the 20th century. Corn is one of the most important crops in global agriculture, in part because of the widespread use of hybrid seeds that have high yields.

Knowledge gained from this research can also be extended to wheat and barley, two important cereal grains.

“A more detailed understanding of the molecular basis of pollen development and male fertility enables improvements in seed production, including hybrid seeds; in the grasses, hybrid corn and rice have significantly boosted world food production,” Meyers said. “Outcomes could include new genetic pathways for more precise control of male fertility and plants with fertility that is more resilient to distressed environments.”

Prior work demonstrated that these small RNAs are required for robust male fertility under even slightly stressful temperature changes. The project focuses on corn anthers because of the ease of staging and dissection, the numerous developmental mutants with cloned genes and the importance of understanding male fertility to the production of hybrid corn seed.

Imaging as a critical component of the work

Caplan’s role in the project will be to determine where these small RNAs are localized within the anther using advanced imaging techniques. Specifically, his team’s work will shed light on where these small RNAs are processed and expressed within each cell, and where they are located within the different tissue layers of the anther over time.

Caplan’s group has developed a method to produce a full 3D rendering of the whole anther, allowing the researchers to visualize the distribution of these small RNAs over the crop’s development.

“Anthers on corn are small in size but they have this beautiful organization that develops as different small RNAs are expressed at various times during the anther’s development,” said Caplan, who also directs the bioimaging center at the Delaware Biotechnology Institute, located near UD’s Newark campus. “Imaging can help visualize and quantify these small RNA developments in relation to other things happening within the cell, and inform understanding of how these small RNAs regulate pollen development.”

The research project will also include training of students in plant and computational biology via continued integration with long-running and successful undergraduate and high school internship programs.

About The Donald Danforth Plant Science Center

Founded in 1998, the Donald Danforth Plant Science Center is a not-for-profit research institute with a mission to improve the human condition through plant science. Research, education and outreach aim to have impact at the nexus of food security and the environment and position the St. Louis region as a world center for plant science. The center’s work is funded through competitive grants from many sources, including the National Institutes of Health, U.S. Department of Energy, National Science Foundation, and the Bill & Melinda Gates Foundation.

Photo illustration by Christian Derr