Figure 1.

Cu²⁺ enhances resistance to potato late blight caused by Phytophthora infestans. (a) Leaves treated with 0.1, 1, and 10 μM of CuSO₄ 4 hr prior to P. infestans inoculation. Images were photographed at 3 days post‐inoculation. Bar = 2 cm. (b) The disease index analysis for pretreatment with 0.1, 1, and 10 μM of CuSO₄. Data represent the mean ± SD (n = 10). (c) The biomass level analysis of the potato leaves pretreated with 0.1, 1, and 10 μM of CuSO₄. The level of PiO8 element and StEF1 were used to quantify the level of P. infestans and plant cells by quantitative PCR. Data represent the mean ± SD (n = 3). (d) Callose deposition in the leaves of potato plants at 12 hr treated with CuSO₄ (10 μM) or control (CK, MgSO₄). (e) Superoxide accumulation in the leaves at 2 hr treated with CuSO₄ (10 μM) or control (MgSO₄). The blue formazan precipitate indicates superoxide production. The asterisks in (b) and (c) indicate a significant difference compared with the control (t test; *p < .05; **p < .01). The experiments were repeated three times with similar results