Air plant genomes shed light on photosynthesis innovation

Photosynthesis requires the uptake of CO2.In land plants, however, gas permeability is a doubleedged sword.Opening stomata facilitates CO2 exchange, but also allows water to evaporate.To support photosynthesis under water limitations, some plants have evolved a workaround process termed Crassulacean Acid Metabolism (CAM).CAM allows plants to stockpile CO2 at night, in the form of malate, when darkness and cooler temperatures lessen the burden of water loss through transpiration.Additionally, CAM concentrates CO2 which promotes the efficiency of Rubsico in producing sugars (Wickell et al. 2021).Despite the complexity required, over 30 different plant families have independently rearranged their physiology for variations of CAM (Silvera et al. 2010).The genetic features that drive the independent evolution of this metabolic process in diverse lineages are not well understood.This is especially vital as understanding the evolution of CAM may lead to strategies to increase crop resilience to drought (Borland et al. 2014).