Drought and ABA treatment inhibit the ubiquitination and degradation of MdbHLH160. A) MdbHLH160 degradation was inhibited in response to PEG and ABA treatment. MdbHLH160-HA transgenic calli were treated with PEG and ABA. Samples of calli were taken at specified time points, and total proteins were extracted and then used for immunoblotting assays using the anti-HA antibody. MdActin was used as a loading control. B) Degradation curve analysis of MdbHLH160-HA using the band intensity (gray value) in (A). Band intensity was determined using ImageJ software. C) Ubiquitination assays of MdbHLH160. The protein extracts of the calli (treated with PEG or ABA for 6 h, +MG132) were used for immunoprecipitation using anti-HA magnetic beads. Immunoprecipitated samples were then detected using anti-HA (top) and anti-Ubi (bottom) antibodies.