Microscopic pores on the surface of plants, called stomata, allow the plants to uptake carbon dioxide (CO2) from the atmosphere and facilitate the transport of water from their roots up to their leaves where it exits through the pores as water vapor. Generally, the pores open during the day, when the plant uses sunlight and CO2 in the process of photosynthesis, and close at night to conserve water. These processes are not only vital for the plant’s health and survival but are also key drivers of global carbon and water cycles, according to Penn State Professor of Biology Charles Anderson, who received a $1.45 million grant from the National Science Foundation to study how to improve these processes.
Grasses — including staple food crops like wheat and maize — have developed specialized stomata that can open and close more rapidly. Researchers believe that the fast-acting stomata in grasses may help them to use water more efficiently, which in turn may have allowed them to colonize dryer environments, such as the Great Plains of North America. Understanding the cellular and biomechanical changes that allow these specialized stomata to function could help in the development of drought-resistant crops, a crucial step to ensuring food safety for the ever-growing human population as the climate warms and becomes more unstable.
“How these stomata open and close has implications for the ability of the plant to draw down CO2 from the atmosphere, which is important for addressing global climate change,” Anderson said. “It also has implications for the ability to grow grasses — including food crops — under limiting water conditions. As we learn how these stomata work, we could potentially develop plants that produce ‘more crop per drop’ and that capture more CO2 from the atmosphere.”
Anderson is leading research into the structure and function of stomata in grasses, bringing together a multidisciplinary team that includes James Z. Wang, distinguished professor of information sciences and technology, and Hojae Yi, assistant research professor of agricultural and biological engineering, at Penn State; as well as collaborators Deborah Petrik at Northeastern State University in Oklahoma and Joseph Turner at the University of Nebraska, Lincoln.
Grasses belong to the group of flowering plants known as monocots — named for the single embryonic leaf that develops in their seeds — and have four-celled stomatal complexes. Stomata in eudicots, a different group of flowering plants that develop two embryonic leaves, are flanked by just two cells.
“We’ve been mostly studying stomata in eudicots in our prior research,” Anderson said. “This new grant will allow us to apply many of the lessons we’ve learned in studying eudicots to developing a better understanding of how the stomata in monocots function.”
The researchers have identified three main goals of the research supported by the grant. First, they will measure and model how the components that make up the cell walls of the four cells in grasses’ stomata enable these cells to expand and contract to open and close the stomatal pores. They will then assess how the cell walls contribute to the rapid response of stomata in grasses by experimentally manipulating the cell wall architecture in these cells. Finally, they will apply what they have learned to design and test grass stomata with enhanced flexibility, responsiveness and dynamic range for improved water use efficiency and photosynthesis.
“I am excited that, with this grant, we will be able to purchase and use a LI-COR instrument,” said Leila Jaafar, a doctoral student working with Anderson whose dissertation research is supported by the grant. “A LI-COR instrument measures gas exchange and the fluorescence of chlorophyll in leaves and will allow us to evaluate photosynthesis and water usage at the level of the whole organism. This will give us a better understanding of how our experiments impact the plant’s physiology. Working with the multidisciplinary team on this project has already been extremely fruitful, it’s a great environment for me to develop as a scientist.”
In addition to training doctoral and master’s students, the grant will provide hands-on experience to undergraduate students in the Penn State Department of Biology’s first-year research initiative (FRI). The FRI is a two-semester lab course sequence that gives students an authentic research experience and connects them with faculty in the Eberly College of Science. As part of its education and outreach mission, the grant will also support a senior-level course-based undergraduate research experience (CURE) taught at Northeastern State University, high school outreach and research mentoring conducted by the Penn State team, and a summer program at the University of Nebraska, Lincoln, providing enrichment and hands-on training in bioengineering to middle school students.
“We’re excited to continue working with students at multiple stages of their education, not only because it’s a great experience for them, but also because of the great ideas and new perspectives that they bring to the work,” Anderson said. “It’s really a win-win scenario. We get to mentor and hopefully inspire a new generation of scientists and science-literate citizens while our research benefits from their intellectual contributions.”