Edited by Joseph JezGlycosylation and deglycosylation are impressive mechanisms that allow plants to regulate the biological activity of an array of secondary metabolites. Although glycosylation improves solubility and renders the metabolites suitable for transport and sequestration, deglycosylation activates them to carry out biological functions. Herein, we report the functional characterization of CsBGlu12, a -glucosidase from Crocus sativus. CsBGlu12 has a characteristic glucoside hydrolase 1 family (␣/) 8 triose-phosphate isomerase (TIM) barrel structure with a highly conserved active site. In vitro enzyme activity revealed that CsBGlu12 catalyzes the hydrolysis of flavonol -glucosides and cello-oligosaccharides. Site-directed mutagenesis of any of the two conserved catalytic glutamic acid residues (Glu 200 and Glu 414 ) of the active site completely abolishes the -glucosidase activity. Transcript analysis revealed that Csbglu12 is highly induced in response to UV-B, dehydration, NaCl, methyl jasmonate, and abscisic acid treatments indicating its possible role in plant stress response. Transient overexpression of CsBGlu12 leads to the accumulation of antioxidant flavonols in Nicotiana benthamiana and confers tolerance to abiotic stresses. Antioxidant assays indicated that accumulation of flavonols alleviated the accretion of reactive oxygen species during abiotic stress conditions. -Glucosidases are known to play a role in abiotic stresses, particularly dehydration through abscisic acid; however, their role through accumulation of reactive oxygen species (ROS) scavenging flavonols has not been established. Furthermore, only one -glucosidase 12 homolog has been characterized so far. Therefore, this work presents an important report on characterization of CsBGlu12 and its role in abiotic stress through ROS scavenging.Plants are sessile organisms that cannot escape their predators and the harsh environmental conditions. However, during the course of evolution, plants have learned to defend themselves and adapt to different types of biotic and abiotic stresses by synthesizing a diverse assortment of secondary metabolites. Many of these secondary metabolites are stored in inactive glycosylated forms. The glycosylation chemically stabilizes and enhances the solubility of the metabolites and renders them fit for storage in the vacuole and more so to protect the plant from the noxious effects of its own defense system (1). These glyconjugates are activated by the hydrolysis of the -glucosidic bond by a class of enzymes called -glucosidases. -Glucosidases (EC 3.2.1.2.1) belong to family 1 of glycoside hydrolases and perform diverse and vital functions in plants, which include, but are not limited to, the activation of lignin precursors (2), release of glucose from oligosaccharides (3), release of phytohormones from inactive glycosides (4), and activation of several defense compounds (5-9). This process of glycosylation and deglycosylation offers an efficient mechanism that regulates the homeostasis of secon...