Pennsylvania State University researchers, in collaboration with an international team of scientists, have unveiled a groundbreaking discovery in plant biology. For the first time, they have identified the molecular messengers that regulate how plants “breathe” and “eat,” a revelation that could significantly impact agricultural practices. This study, led by Penn State and published in the journal Nature Plants on August 25, could pave the way for enhancing plant resilience and crop yields.
“This discovery significantly advances our understanding of how plants coordinate their internal metabolism – the chemical reactions they use to make energy – with their external environment, a fundamental process for plant growth and survival,” said Sarah Assmann, Waller Professor of Plant Biology at Penn State and corresponding author of the study. “Our findings open doors for future research into improving plant resilience and crop yields.”
Understanding Plant Communication
For decades, scientists have sought to understand the communication between the internal cells of a leaf and its guard cells. These specialized cells control the opening and closing of stomata, the microscopic pores on the leaf surface that manage crucial processes such as energy production and water loss. Stomata act as tiny “mouths” on leaves, regulating the intake of carbon dioxide (CO2) necessary for photosynthesis and the release of water vapor back into the atmosphere.
Assmann explained that while it was known that guard cells respond to light, which drives photosynthesis, the identity of the chemical “messenger” guiding this process had remained elusive. “There is always a tradeoff for terrestrial plants between maximizing CO2 intake, which is needed for photosynthesis, and letting out water vapor, which can dry out the plant and ultimately kill it if it loses too much water,” Assmann said. “The stomata are the pores where that tradeoff takes place.”
The Role of Sugars and Maleic Acid
The research team conducted their study on mouse-ear cress (Arabidopsis thaliana) and fava beans (Vicia faba), revealing that sugars and maleic acid are crucial messengers in this process. Through a series of meticulous experiments, they identified a molecular feedback loop between photosynthetic activity and stomatal regulation.
By extracting apoplastic fluid from leaves exposed to red light, which stimulates high photosynthesis, or darkness, the researchers analyzed its chemical composition. They identified 448 unique chemical compounds, many of which are essential for basic plant functions. “We identified hundreds of metabolites in apoplastic fluid, which no one had analyzed to this extent before,” Assmann noted. “That, on its own, is an important contribution to the field.”
“We identified hundreds of metabolites in apoplastic fluid, which no one had analyzed to this extent before,” Assmann said. “That, on its own, is an important contribution to the field, independent of the research question that we specifically were addressing, because it gives a lot of leads on other potential signaling molecules for processes throughout the plant.”
Implications for Agriculture and Future Research
Through extensive analysis, the researchers found that sugars such as sucrose, fructose, and glucose, along with maleic acid, increased under red light, which activates photosynthesis. These metabolites were shown to enhance stomatal opening, a critical factor in plant metabolism. The team conducted further experiments, confirming that sugars signal stomata to open more widely, thus providing a complete picture of this internal communication process within plants.
“We’re focused on understanding how plants sense and respond to environmental conditions,” Assmann stated. “Plants can’t uproot themselves and find somewhere else to live; they have to deal with whatever the environment throws at them – increasingly drought and heat stress – so we study what makes plants resilient, from the very specific molecular level all the way up to whole plant physiology and field experiments, with the goal of improving crop productivity.”
The study, funded by the U.S. National Science Foundation, included contributions from Penn State’s doctoral student Yunqing Zhou, Associate Professor Timothy Jegla, and postdoctoral scholars Mengmeng Zhu and Yotam Zait. Collaborators from The Hebrew University of Jerusalem, Nagoya University in Japan, the RIKEN Center for Sustainable Resource Science, and the University of Mississippi also played significant roles.
At Penn State, researchers are tackling real-world problems that affect global health, safety, and quality of life. The university’s research efforts are bolstered by federal support, which has historically driven innovation and competitiveness. However, recent federal funding cuts pose a threat to this progress, underscoring the importance of continued investment in scientific research.
For more information on the implications of federal funding cuts, visit Research or Regress.
