Designing Drought Resistant Crops with Crassulaceous Acid Metabolism (CAM) Photosynthesis

PICTURE: First author of the research article After

Credit: George Ratcliffe

The ASPB is pleased to announce the publication of outstanding research on water-efficient alternatives for photosynthesis in temperate environments, which are likely to become hotter and drier in the future.

Drought causes severe crop losses in many parts of the world, and climate change threatens to exacerbate the occurrence of drought in both temperate and arid regions. In a new book published in The plant cellDr Nadine Töpfer of the Leibniz Institute for Plant Genetics and Crop Research, along with colleagues from the University of Oxford in the UK, analyzed the potential for creating drought-resistant plants through the Introduction of Crassulacean Acid Metabolism (CAM). They used a sophisticated mathematical modeling approach to study the effects of introducing CAM photosynthesis, which is used by plants able to thrive in arid conditions, in C3 plants, which tend to thrive only in areas where the sun’s intensity and temperatures are moderate and water is plentiful.

Most plants, including some field crops such as rice, wheat, oats, and barley, utilize C3 carbon uptake, in which the CO2 absorbed during the day by the pores of the leaf stomata is used immediately in light-induced photosynthesis reactions. Unfortunately, this results in significant water loss through these pores in hot, dry conditions. CAM is an alternative carbon binding pathway that temporarily separates CO2 uptake from carbon uptake, allowing the plant to open stomata for CO2 uptake in the cool of the night and store carbon inside. The CAM plant then closes its stomata during the heat of the day to minimize water loss and releases the CO2 stored inside the leaf cells to be used for light-powered photosynthesis during the day.

Using simulations under a range of temperature and relative humidity conditions, the authors posed the question: Would full CAM or alternative water saving methods be more productive in environments where C3 crops are typically grown? They discovered both that the vacuolar storage capacity in a leaf is a major factor limiting the efficiency of water use during CAM and that environmental conditions shape the occurrence of different phases of the CAM cycle. . Mathematical modeling has also identified an alternate CAM cycle that involves mitochondrial isocitrate dehydrogenase as a potential contributor to initial carbon uptake at night.

Lead author Nadine Töpfer, who carried out the work during the tenure of a Marie-Curie Postdoctoral Fellowship in Prof. Lee Sweetlove’s group at Oxford, said: “Modeling is a powerful tool for exploring complex systems and it provides information that can guide the lab and the field. I think our results will provide encouragement and ideas to researchers who aim to transfer the water conservancy character of CAM plants to other species. “

Their results revealed not only that the water-saving potential of CAM photosynthesis strongly depends on the environment, the diurnal environment being more important than that at night, but also that of alternative metabolic modes, distinct from those of the natural CAM cycle, can be beneficial under certain conditions such as shorter days with less extreme temperatures. This timely work provides valuable information that will help us prepare for the challenges of growing food crops in increasingly hot and drier temperate environments.


Full citation:

Nadine Töpfer, Thomas Braam, Sanu Shameer, R. George Ratcliffe, Lee J. Sweetlove. Alternative CAM modes provide environment specific water saving benefits in a leaf metabolic model. Plant cell DOI: https: //10.1105/tpc.20.00132.

Image credit: George Ratcliffe

About the researchers:

To arrange an interview with the authors, please contact Nadine Töpfer
[email protected]

Information on the funder:

Marie Sklodowska
Individual Curie scholarship

About the plant cell

The plant cell publishes new research of particular importance in plant biology, particularly in the fields of cell biology, molecular biology, biochemistry, genetics, development and evolution. The main criteria for publication are that the article offers new insight that is of broad interest to plant biologists, not just specialists, and that the presentation of the results is appropriate for a wide audience of plant biologists.

About the American Society of Plant Biologists (ASPB)

The ASPB is a professional scientific society, headquartered in Rockville, Maryland, dedicated to the advancement of plant science around the world. With a staff of approximately 4,500 plant scientists from across the United States and over 50 other countries, the Society publishes two of the most widely cited journals in plant science: The Plant Cell and Plant Physiology. For more information on the ASPB, please visit Also follow the ASPB on Facebook at and on Twitter @ASPB.

For more information please contact:

Nancy Eckardt

Senior Feature Editor, The Plant Cell

[email protected]

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