In a groundbreaking study that challenges long-standing assumptions in plant biology, researchers at Michigan State University have uncovered a vital link between photorespiration and the synthesis of folates—a class of essential nutrients that include vitamin B9, widely recognized for its role in preventing birth defects. This revelation redefines photorespiration, historically dismissed as a wasteful and counterproductive process, as a critical metabolic pathway with profound implications for human nutrition and agriculture in the era of climate change.
Photorespiration occurs when the enzyme rubisco, which primarily catalyzes the fixation of atmospheric carbon dioxide (CO₂) into organic molecules during photosynthesis, mistakenly binds oxygen instead. This error generates a toxic byproduct known as phosphoglycolate that interrupts the photosynthetic process. Plants have evolved a complex recycling mechanism to neutralize and repurpose this compound through photorespiration, but the full scope of its biological importance has remained elusive until now.
The MSU team, led by associate professor Berkley Walker, employed cutting-edge metabolic flux analysis techniques combined with mass spectrometry to quantify the carbon flux through photorespiration with unprecedented precision. Using the model organism Arabidopsis thaliana, they measured the incorporation of CO₂ into various metabolic intermediates under conditions that either permitted or suppressed photorespiration. This approach provided a clear picture of how carbon atoms travel through metabolic networks to support folate biosynthesis.
Their data revealed that approximately 6 percent of the carbon absorbed by the plant’s leaves is funneled through photorespiration toward the production of folates, a critical nutrient group including the prenatal vitamin B9. When photorespiration was experimentally suppressed, this carbon flux dropped dramatically—by nearly fivefold—highlighting the indispensable role of photorespiratory metabolism in sustaining folate synthesis.
Folate molecules play a fundamental role in human development, particularly during pregnancy, by preventing neural tube defects and facilitating cellular growth and repair. Thus, the discovery that photorespiratory pathways contribute substantially to folate production in plants carries significant nutritional implications. It raises concerns that rising atmospheric CO₂ levels, driven by climate change, may inadvertently reduce the nutritional quality of staple crops by decreasing the reliance on photorespiration.
Under elevated CO₂ conditions, plants tend to favor direct carbon fixation over photorespiration due to reduced oxygenation activity by rubisco. The MSU study quantified this shift, demonstrating that folate production via photorespiration could decline from around 6 percent to as low as 1 percent in such environments. This numerical decrease is not trivial; it suggests that as atmospheric CO₂ levels soar, the vitamin content in essential crops like rice and wheat might diminish, compromising dietary vitamin B9 intake for millions globally.
The research further delves into the enzymatic and biochemical pathways linking photorespiration with one-carbon metabolism, revealing a tightly integrated network where carbon atoms diverted from photorespiration feed into folate biosynthetic routes. These insights illuminate a complex metabolic choreography where seemingly disadvantageous biochemical detours are repurposed to support vital nutrient synthesis.
To carry out their measurements, Walker’s team innovatively combined gas exchange analysis—in which an infrared gas analyzer clamps onto leaf surfaces to measure CO₂ uptake—with rapid leaf freezing using liquid nitrogen. This method swiftly halts metabolic reactions, preserving chemical states for detailed mass spectrometry analysis. Such temporal precision allowed for a dynamic view of carbon allocation and metabolic fluxes within the leaf’s biochemistry.
The ramifications of this research extend beyond academic curiosity. By elucidating how plants produce folates and the impact of environmental factors on this process, the findings pave the way toward bioengineering crops with enhanced nutritional profiles. Such innovations could be pivotal in addressing micronutrient deficiencies in populations where supplementation or dietary diversity is limited.
Furthermore, the study underscores the importance of understanding ecological and physiological responses of plants to global changes. The intricate balance between photosynthesis and photorespiration appears more than a biochemical inconvenience; it is a linchpin in sustaining the nutritional fabric of human food supplies. The MSU researchers emphasize that without a deep comprehension of these metabolic interplays, efforts to adapt agriculture to future climates might fall short.
Walker’s team is now poised to expand these investigations into field-grown crops to verify if the lab-based observations hold true under natural environmental conditions. Such endeavors will refine predictions about food quality in a warming world and guide agricultural practices accordingly.
This research, funded by the U.S. National Science Foundation, represents a compelling example of how fundamental plant science can illuminate pathways to mitigate the nutritional challenges posed by climate change. As plants evolve in response to shifting atmospheres, the necessity to adapt human nutrition through scientific innovation becomes ever more urgent.
In summary, this landmark study invites a reconsideration of photorespiration’s role—not as a metabolic burden but as an essential contributor to the biosynthesis of nutrients critical for human health. It opens new avenues in plant metabolic engineering aimed at safeguarding and enhancing vitamin content in a changing global environment.
Subject of Research: Photorespiration’s role in folate biosynthesis and its impact on plant nutrition under varying CO₂ conditions.
Article Title: Metabolic flux analysis in leaf metabolism quantifies the link between photorespiration and one carbon metabolism
News Publication Date: 3-Sep-2025
Web References:
https://www.nature.com/articles/s41477-025-02091-w
http://dx.doi.org/10.1038/s41477-025-02091-w
References:
Walker, B. et al. (2025). Metabolic flux analysis in leaf metabolism quantifies the link between photorespiration and one carbon metabolism. Nature Plants.
Image Credits: Finn Gomez / Michigan State University
Keywords: Climate change adaptation, Plants, Photorespiration, Folate biosynthesis, Vitamin B9, Arabidopsis thaliana, Metabolic flux analysis
