The role of transcription factor MdGeBP3 in Modulating cold stress tolerance and anthocyanin biosynthesis in apple.

Cold stress is a major environmental constraint limiting crop productivity and quality. Here, we identify a transcription factor MdGeBP3 in apple, which responds to cold stress at both transcriptional and post-translational levels. Functional analysis revealed that overexpression of MdGeBP3 significantly enhances cold tolerance in both apple calli and the model plant Arabidopsis, and the transcript levels of cold-responsive genes were induced in MdGeBP3 overexpression plants. Furthermore, MdGeBP3 was found to participate in anthocyanin biosynthesis. Overexpression of MdGeBP3 in Arabidopsis and apple calli promoted anthocyanin accumulation. Moreover, temporary overexpression of MdGeBP3 in both apple leaves and fruit peel led to increased anthocyanin accumulation, while silencing the MdGeBP3 gene via a virus-induced method decreased anthocyanin content. Collectively, these findings demonstrate that MdGeBP3 acts as a positive regulator of cold tolerance and anthocyanin biosynthesis, providing new insights into the coordination between stress responses and secondary metabolism in apple.