CAREER: Defining the evolutionary trajectory of CAM photosynthesis in Portulacineae (Caryophyllales)

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Crassulacean Acid Metabolism (CAM) refers to a set of changes to the photosynthetic pathway that allows plants to grow more efficiently under conditions of drought, high temperatures, and/or low atmospheric CO2. It is biochemically similar to another modification, C4 photosynthesis, but requires fewer structural changes to leaf tissue. We know a great deal about the evolutionary history of the C4 syndrome, and this knowledge has informed efforts to genetically engineer this photosynthetic improvement into crops such as rice. We know virtually nothing about CAM evolution- its genetic underpinnings, its relationship to other plant traits, and whether it is equally likely to evolve in all plant lineages. Here the PI proposes to significantly increase our understanding of how CAM evolves, utilizing a comparative approach and focusing on one horticulturally important plant lineage known for drought tolerance, which includes the cacti. The project involves extensive genetic and ecological analyses, and will also develop a new metric to efficiently screen species for low level CAM activity. Because this is a CAREER award, all research goals of the project are tightly interwoven into an innovative education program involving undergraduates, graduate students, and post-doctoral researchers at Brown University, and graduate students from Peru. In addition to the basic scientific understanding that will be gained, this project should yield valuable insight into the use of CAM photosynthesis for engineering more drought-resistant crops. Moreover it will build a foundational bridge of scientific collaboration between the United States and Peru, and contribute significantly to capacity building and scientific training in a developing nation.