Exogenous H2O2 in Phytoplasma-Infected Potato Plants Promotes Antioxidant Activity and Tuber Production Under Drought Conditions

H2O2-mediated symptoms and antioxidant responses were examined in phytoplasma-infected potato plants under drought conditions. In vitro phytoplasma-infected or uninfected plants were transferred to a greenhouse and sprayed twice a week with H2O2. Phytoplasma decreased water potential, catalase (CAT) activity and increased H2O2 content significantly. H2O2 significantly enhanced minitubers weight and starch content in phytoplasma-infected plants. Under drought conditions, minitubers produced by H2O2-sprayed phytoplasma-infected plants had significantly more starch than the controls. Minitubers weight was reduced in both uninfected and infected plants, but H2O2 in the presence of phytoplasma significantly enhanced minitubers weight, CAT activity, and H2O2 content. H2O2 treatment induced higher internal H2O2 concentration, which was associated with positive effects on infected minitubers, such as weight, reduction of number, starch content, sprouting, and tolerance to drought a signal role for H2O2 in lessening symptoms is suggested.