Establishment of a glucocorticoid inducible system for regulating somatic embryogenesis in Liriodendron hybrids

The precise expression of transcription factors (TFs) is crucial for plant growth and development, especially during somatic embryogenesis. However, conventional overexpression approaches, commonly used for functional genetics, can lead to deleterious effects. Therefore, it is imperative to ensure that TFs are expressed in a controlled and timely manner when aiming to enhance the efficiency of somatic embryogenesis. In this study, a dexamethasone/glucocorticoid receptor (DEX/GR) inducible expression system was employed to modulate the protein expression levels of target TFs within the nucleus during somatic embryogenesis in Liriodendron hybrids. We selected the WUSCHEL (WUS) gene, a well-established functional TF known for its vital role in somatic embryogenesis, as a model to assess the effectiveness of this system. Through DEX treatment, we induced the translocation of LhWUS-GR/LhWUS-GFP-GR fusion proteins from the cytoplasm to the nucleus, consequently leading to WUS-driven somatic embryogenesis. As the DEX concentration increased, there was a corresponding increase in the migration of the LhWUS-GFP-GR fusion protein into the nucleus. Additionally, we observed a higher proliferation ratio of callus expressing LhWUS-GR when exposed to varying DEX concentrations. Notably, the efficiency of somatic embryogenesis exhibited significant improvement under optimal DEX concentration. In conclusion, our study successfully utilizes the DEX/GR inducible system in Liriodendron hybrids, offering a valuable tool for the precise control and utilization of TFs at the desired levels. This innovative approach holds promise for advancing our understanding of TF function and enhancing plant development through the regulated manipulation of TF expression.