David Stern, president of the Boyce Thompson Institute, received a three-year grant totaling $459,950 from the U.S. Department of Agriculture for research to boost photosynthesis in corn plants, to make them more productive, especially in cold temperatures.
Researchers in the Stern laboratory have generated a type of corn that produces high levels of a key enzyme in photosynthesis called Rubisco. Typically, Rubisco levels drop in the cold, but plants with extra Rubisco appear to be more tolerant of cold weather—a characteristic that could be advantageous to northern corn farmers. Many researchers have attempted to improve upon the Rubisco enzyme or to increase Rubisco quantities in crop plants, but have had little success. The USDA grant will enable the Stern laboratory members to better understand how these plants continue to thrive in the cold, and whether excess Rubisco offers any additional benefits to plants, such as higher yield.
Corn plants that can withstand the cold would have a longer growing season, potentially enabling farmers to harvest twice. Additionally, earlier plantings will result in larger plants during the peak of summer, allowing for greater productivity.
“We are delighted to have this opportunity to explore the consequences of increasing Rubisco content in corn,” said Stern. “Photosynthetic capacity and stress tolerance are two key factors in determining crop yield and also factor into sustainability of agricultural practices.”
In prior experiments, former postdoctoral researcher Katia Wostrikoff inserted additional copies of genes into the corn plant that code for the large and small protein subunits that make up the Rubisco enzyme. Research associate Leila Feiz then discovered a chaperone protein that helps assemble the subunits into a functional enzyme, and inserted an extra copy of that gene as well. Analysis of the resulting plants by Coralie Salesse-Smith, a graduate student in the Stern laboratory, showed that the assembled Rubisco localizes in the correct cells of the plant and accumulates to up to 55 percent higher levels than in traditional corn plants.
As part of the newly funded project, Salesse-Smith will work with research fellow Robert Sharwood of the Australian National University in Canberra at the Center of Excellence in Translational Photosynthesis. At the center, the team will use specialized techniques to investigate whether the high-Rubisco corn plants are engaging in greater rates of photosynthesis, and will examine the activity of other related enzymes.
In future work, the researchers will explore the mechanisms within the plant that help it to withstand cold weather and how possessing extra Rubisco affects their growth and metabolism.