Figure 8.

PtrERF9 regulates PtrGSTU17 expression to control ROS levels in response to cold stress. (a–d) PtrGSTU17 expression (a, c) and GST activity (b, d) in lemon wild‐type (WT) and transgenic plants (a, b) and TRV control plants and trifoliate orange VIGS (TRV‐PtrERF9) plants (c, d) before and after cold stress. (e–h) Levels of H₂O₂ (e, g) and O₂ ^·− content (f, h) in transgenic lemon and WT (e, f) and TRV control and VIGS plants (g, h) before and after cold treatment. (i–l) In situ detection of H₂O₂ (i, k) and O₂ ^·− (j, l) in the WT and transgenic lemons (i, j) and TRV control and VIGS plants (k, l) after cold treatment, as revealed by histochemical staining with DAB and NBT, respectively. Error bars indicate ± SE (n = 3). Asterisks indicate significant differences between different groups under the same growth condition (*P < 0.05; ***P < 0.001).