Construction of Agrobacterium-mediated High Frequency Transformation System for Populus tomentosa

Pop ulus tomentosa, as an important economic plant and as a natural host of Agrobacterium tumef aciens, has been used as a model plant for tissue culture and genetic transformation study of xyloghyta. In this work, several important factors influencing the efficiency of Agrobacterium-mediated transformation and regeneration of plants, such as types of explants, concentration of Agrobacterium suspension, wounding treatment on explants, conditions of pre-cultivation and co-cultivation, medium composition etc, were studied, and an Agrobacterium-mediated high frequency system was established for P. tomentosa. After pre-cultivation in the medium MSy for 48 h, the healthy sterile leaves were cut into discs, co-cultivated with suspension of A. tumef aciens LBA4404 at the concentration of 5×108 cells/mL for another 48 h, and then transferred onto the selective media containing appropriate antibiotics. The average transformation frequency of kanamysin resistant(Kmr) calli was up to 56.2%, and the ratio of the number of transgenetic plants to the number of explants was up to 19.9%. Only by wounding treatment alone, the transformation frequency was improved by 20~40%. With this transformation system, NP-1, a disease resistant gene, was successfully introduced into P. tomentosa and a lot of transgenetic plants were obtained.