A roadmap for research on crassulacean acid metabolism (<scp>CAM</scp>) to enhance sustainable food and bioenergy production in a hotter, drier world

<jats:title>Summary</jats:title><jats:p>Crassulacean acid metabolism (<jats:styled-content style="fixed-case">CAM</jats:styled-content>) is a specialized mode of photosynthesis that features nocturnal <jats:styled-content style="fixed-case">CO</jats:styled-content><jats:sub>2</jats:sub> uptake, facilitates increased water‐use efficiency (<jats:styled-content style="fixed-case">WUE</jats:styled-content>), and enables <jats:styled-content style="fixed-case">CAM</jats:styled-content> plants to inhabit water‐limited environments such as semi‐arid deserts or seasonally dry forests. Human population growth and global climate change now present challenges for agricultural production systems to increase food, feed, forage, fiber, and fuel production. One approach to meet these challenges is to increase reliance on <jats:styled-content style="fixed-case">CAM</jats:styled-content> crops, such as <jats:italic>Agave</jats:italic> and <jats:italic>Opuntia</jats:italic>, for biomass production on semi‐arid, abandoned, marginal, or degraded agricultural lands. Major research efforts are now underway to assess the productivity of <jats:styled-content style="fixed-case">CAM</jats:styled-content> crop species and to harness the <jats:styled-content style="fixed-case">WUE</jats:styled-content> of <jats:styled-content style="fixed-case">CAM</jats:styled-content> by engineering this pathway into existing food, feed, and bioenergy crops. An improved understanding of <jats:styled-content style="fixed-case">CAM</jats:styled-content> has potential for high returns on research investment. To exploit the potential of <jats:styled-content style="fixed-case">CAM</jats:styled-content> crops and <jats:styled-content style="fixed-case">CAM</jats:styled-content> bioengineering, it will be necessary to elucidate the evolution, genomic features, and regulatory mechanisms of <jats:styled-content style="fixed-case">CAM</jats:styled-content>. Field trials and predictive models will be required to assess the productivity of <jats:styled-content style="fixed-case">CAM</jats:styled-content> crops, while new synthetic biology approaches need to be developed for <jats:styled-content style="fixed-case">CAM</jats:styled-content> engineering. Infrastructure will be needed for <jats:styled-content style="fixed-case">CAM</jats:styled-content> model systems, field trials, mutant collections, and data management.</jats:p>