MdBT2 negatively regulates the MdbHLH160-mediated drought tolerance and the transcriptional activation of downstream target genes. (A to C) Growth phenotypes A), fresh weight B), and O₂⁻C) content of different types of transgenic calli under PEG treatment. Bars = 1 cm. D to E) Dual-LUC assays in N. benthamiana leaves. “–” represents the corresponding EV. The data are presented as the means ± SD of 3 biological replicates. Bars with different letters are significantly different at P < 0.05, according to 1-way ANOVA and Duncan's tests.