*2.2. Analysis of H2O2 Levels*

The H2O2 content of sweet potato leaves was assessed using the xylenol orange method [22]. A total of 0.1 g of leaf tissue was ground and homogenized in a solution of 50 mM potassium phosphate buffer (pH 6.5) and 1 mM hydroxylamine. The homogenate was centrifuged at 12,000× *g* for 15 min at 4 ◦C. A total of 100 μL of the supernatant was added to a reaction mixture containing ferric ammonium sulfate (FeNH4[SO4]), 25 mM sulphuric acid, 250 μM xylenol orange, and 100 mM sorbitol. After 30 min in the dark at room temperature for incubation, the absorbance of the samples was determined at 560 nm. H2O2 measurements were expressed as relative values by control and treatment.
