Efficient Agrobacterium-Mediated Transformation of the Commercial Hybrid Poplar Populus Alba × Populus glandulosa Uyeki

Transgenic technology is a powerful tool for gene functional characterization, and poplar is a model system for genetic transformation of perennial woody plants. However, the poplar genetic transformation system is limited to a number of model genotypes. Herein, we developed a transformation system based on efficient Agrobacterium-mediated transformation for the hybrid poplar Populus Alba × Populus glandulosa Uyeki, which is a fast-growing poplar species that is suitably grown in the northern part of China. Importantly, we optimized many independent factors and showed that the transformation efficiency was improved significantly using juvenile leaf explants. Explants were infected by an Agrobacterium suspension with the OD(600) = 0.6 for 15 min and then co-cultured in dark conditions for 3 days. Using the improved transformation system, we obtained the transgenic poplar with overexpression of β-glucuronidase (GUS) via direct organogenesis without callus induction. Furthermore, we analyzed the GUS gene in the transgenic poplars using PCR, qRT-PCR, and GUS staining. These analyses revealed that the GUS gene was efficiently transformed, and it exhibited various expression levels. Taken together, these results represent a simple, fast, and efficient transformation system of hybrid poplar plants. Our findings may facilitate future studies of gene functions in perennial woody plants and tree breeding via transgenic technology assisted design.