How Plants React to Elevated CO2: The Impacts of Climate Change on Crops

As carbon dioxide levels increase, scientists have long wondered exactly how these elevated gas levels might impact plants. Now, scientists have solved a long-standing mystery concerning the way plants reduce the numbers of their breathing pores in response to rising CO2 levels in the atmosphere.

"For each carbon dioxide molecule that is incorporated into plants through photosynthesis, plants lose about 200 hundred molecules of water through their stomata," said Julian Schroeder, the researcher who headed the study, in a news release. "Because elevated CO2 reduces the density of stomatal pores in leaves, this is, at first sight beneficial for plants as they would lose less water. However, the reduction in the numbers of stomatal pores decreases the ability of plants to cool their leaves during a heat wave via water evaporation. Less evaporation adds to heat stress in plants, which ultimately affects crop yield."

In order to better understand how CO2 impacts stomata, the tiny pores in a plant's leaves, the researchers turned to a mustard plant called Arabidopsis. The researchers isolated proteins which, when mutated, abolished the plant's ability to respond to CO2 stress.

The researchers found that when plants sense atmospheric CO2 levels rising, they increase their expression of a key peptide hormone called Epidermal Patterning Factor-2, or EPF2. This peptide acts like a morphogen which alters stem cell character in the epidermis of growing leaves and blocks the formation of stomata.

Because other proteins known as proteases are needed to activate EPF2, the researchers also used a "proteomics" approach to identify a new protein that they called CRSP (CO2 Response Secreted Protease) which is crucial for activating the EPF2 peptide.

The findings of these proteins and genes have the potential to address a wide range of critical agricultural problems in the future. As the climate changes, it's crucial to understand how plants respond to elevated gas levels and how farmers can develop strategies in order to help mitigate climate impacts when it comes to growing food crops.

The findings are published in the journal Nature.