β-Glucosidases: Multitasking, moonlighting or simply misunderstood?

beta-Glucosidases have a wide range of functions in plants, including roles in recycling of cell-wall oligosaccharides, defense, phytohormone signaling, secondary metabolism, and scent release, among others. It is not always clear which one is responsible for a specific function, as plants contain a large set of beta-glucosidases. However, progress has been made in recent years in elucidating these functions. To help understand what is known and what remains ambiguous, we review the general approaches to investigating plant beta-glucosidase functions. We consider information that has been gained regarding glycoside hydrolase family 1 enzyme functions utilizing these approaches in the past decade. In several cases, one enzyme has been assigned different biological functions by different research groups. We suggest that, at least in some cases, the ambiguity of an enzyme's function may come from having multiple functions that may help coordinate the response to injury or other stresses. (C) 2015 Elsevier Ireland Ltd. All rights reserved.