Abstract
Certain plant lineages increase their environmental fitness by producing specialized metabolites via acquisition of novel enzyme functions. Flavonoids are major secondary metabolites widespread in land plants, and are most commonly conjugated with various sugar moieties by UDPsugar dependent glycosyltransferases (UGT) in a lineage-specific manner. For instant, flavonoid glucuronosyltransferases responsible for specialized metabolites (flavonoid glucuronide) in distinct plant lineages; e.g. perilla, daisy, and grapevine have differentiated independently from each parental glucosyltransferase by acquisition of different Arg residue required for their sugar donor specificity changes. Thus, the plasticity of sugar donor specificity of UGT explains, in part, the extraordinary structural diversification of phytochemicals observed in nature.
