Antioxidant Enzyme Activities in Potato Leaves

The activity of PAL was used as an important metabolic process indicator in potatoes. The total SOD activity in potato leaves was determined using a kit (A001-1, Nanjing Jiancheng Bioengineering Institute, Nanjing, China) based on the nitrobluetetrazolium method according to the manufacturer’s instruction, as shown in a previous report [37 (link)]. The POD activity was measured by using a POD assay kit (A084-3-1; Nanjing Jiancheng Bioengineering Institute, Najing, China) on the basis of guaiacol oxidation at 470 nm by H₂O₂ according to the manufacturer’s instruction, as shown in a previous report [38 (link)]. Similarly, the activity of CAT was also measured using a CAT assay kit (A007-1; Nanjing Jiancheng Bioengineering Institute, China) as seen in a report [38 (link)]. The PAL can catalyze L-phenylalanine to produce trans-cinnamic acid and ammonia, and the maximum absorption peak of trans-cinnamic acid is 290 nm. PAL activity was calculated by measuring the increase in the OD value to 290 nm using a PAL assay kit (E-BC-K522-S; Elabscience Biotechnology Co. Ltd, China). As there was no POD, CAT, and PAL activity in P. infestans through test kits, the SOD activity of P. infestans was used as the antioxidant system indicator in P. infestans.