Glycosylation of plant secondary metabolites: Regulating from chaos to harmony

Plants respond to stress by forming a coordinated defense process from a seemingly chaotic response. Molecular glycosylation is the most common and extensive type of modification reaction in plants. This review adds to the description of glycosylation and corresponding glycosyltransferases (GTs) in plants during defense versus growth, which are relatively uncharted in comparison with other plant defense regulations. A variety of small-molecule compounds colored by GTs play an important role in buffering the effects of biotic and abiotic stresses on plants. Autotoxicity defense compounds are stored in the form of inactive glycosides in a defense reaction to release toxic aglycones and produce cascade effects. Through continuous analysis, the crystal structures of GTs, the details of the interaction between enzymes and substrates, and their catalytic mechanism have been revealed, providing a basis for further elucidating the specificity of substrates.