Review: Secrets of succulence ($)

“Succulence is a phenomenon that has long eluded a decisive consensus definition,” begins Males in his review of the physiology and evolutionary developmental biology of succulence. Succulence can broadly be defined as the storage of water such that the plant can maintain physiological activity in the absence of an external supply (in other words, drought avoidance), but where and how this water is stored is highly variable. Furthermore, succulence has evolved many times independently, so the trait of succulence is quite diverse. The author describes the variables that affect the physiology of succulent water use, which include specialized cells and tissues, short-lived roots, and the dynamic regulation of aquaporins, as well as efforts to map these traits to genes, and the “complex relationship” between succulence and CAM, the specialized form of photosynthesis found in many but not all succulent plants.  J. Exp. Bot. 10.1093/jxb/erx096