GardenDrumPhotosynthetic metabolism changed by increasing CO2 levels

Sarracenia purpurea Photographer François MEY. Herbarium of Museum National d'Histoire Naturelle

Sarracenia purpurea Photographer François MEY. Herbarium of Museum National d’Histoire Naturelle

Ever wondered why well-kept herbarium specimens are still useful in this digital age? New research using them shows that the way plants photosynthesise has shifted over the course of the past century as atmospheric CO2 levels continue to rise.

Scientists at Umeå University and the Swedish University of Agricultural Sciences developed a way using NMR spectroscopy to deduce biochemical regulation in historical herbarium specimens, including both crops and wild plant species.

Plants form intramolecular isotope patterns of glucose during photosynthesis, and changes in these isotope patterns are linked to changes in metabolic fluxes depending on the different CO2 levels. The method was first calibrated in greenhouse experiments and then used to compare historic and modern plant samples, allowing the researchers to track changes in metabolism over centuries.

Photosynthesis in plants and their uptake of CO2 is balanced by another process called photorespiration. During the past 100 years, the herbarium specimens showed that this balance has moved towards greater photosynthesis, correlating with rise in global levels of carbon dioxide.

As photosynthesis increases the plant’s uptake of carbon dioxide, this photosynthesis of plants around the world has been able to mitigate the effects of climate change. However, the news is not all good, as photorespiration increases with higher temperatures, meaning that as the world continues to warm, the balance should shift back away from photosynthesis to photorespiration.

More at Umeå University News

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