Fig. 2. Change in absorbance across time for a wheat cultivar with high (Penawawa —•—) or low (ID377s, ——) seed polyphenol oxidase levels. The assay used three seeds incubated with 1.5 mL of 50 mM 3-(N-morpholino) propane sulfonic acid (MOPS) buffer (pH 6.5) containing 10 mM 3,4 dihydroxyphenylalanine (L-DOPA) in 2-mL microcentrifuge tubes with constant rotation. Absorbance values are the average of three replicate assays measured at 475 nm at the time points indicated. Error bars indicate one standard deviation above and one below the mean value. Where no error bars are apparent, they are less than the size of the symbol, on the order of SD <0.008 absorbance units.