The activity of ß-glucuronidase (GUS) can be accurately determined in intact plant tissue using 4-methylumbelliferyl ß-D-glucuronide (4-MUG) as a substrate. Upon hydrolysis by GUS, the fluorochrome 4-methyl umbelliferone (4-MU) is produced. This method is based on the permeability of both 4-MUG and 4-MU through plant tissue. It consists of incubation of the tissue with the reagent and quantification of the fluorescence emitted by 4-MU in the solution. GUS activity in each sample can be...
