Abstract
Poplar is cultivated widely for pulpwood, firewood, and timber. Transgenic poplar may be part of a solution for wood demand in China. Because transgene escape is an important part of ecological security evaluation of transgenic plants, in this chapter we discuss a real transgenic poplar case study. In this case study, mature transgenic male Populus nigra plants harbored a Bacillus thuringiensis toxin gene (i.e. Bt poplar). A plantation of these plants served as a testbed for a relevant example for gene flow monitoring in China. Furthermore, we discuss environmental risk assessment (ERA) of these transgenic plants. While transgenes can drift to related species through natural and controlled pollination, the probability of transgene drift appears to be very low in the field. The resultantBt poplar seeds occurred at a frequency from about 0.15% at 0 m to about 0.02% at 500 m away from the Bt poplar. The Bt poplar progeny seeds had decreased germination within 3 weeks in the field (from 68% to 0%), compared with the 48% germination rate after 3 weeks at 4°C. The survival rate of seedlings in the field was 0% without any treatments, but increased to 1.7% under four combined treatments (clean and trim, watering, weeding, and cover with plastic to retain moisture) after being seeded in the field for 8 weeks. Hybrid offspring appeared to possess segregated traits following artificially controlled pollination. While hybrids of transgenic poplar and non-transgenic poplar can be excellent germplasm, gene flow should be monitored. Transgene expression in grafted scion and rootstock of transgenic poplar is reviewed. The transgenic poplar studied appears to be safe; no ecological or environmental harm has been observed in China.