Bt poplar in China
Genetically engineered black poplars (P. nigra) have been cultivated commercially in China since 2001. The trees produce the insecticidal protein Cry1Ac. In 2011, the official acreage of Bt poplar was 495 hectares. Between 2001 and 2003 a further 400.000 white poplar hybrids that also produce Bt toxins were planted. According to available information, these trees are sterile.
In 2004, the first published reports appeared on transgene introgression into neighbouring poplar plantations in the North-Western province of Xinjiang, where field trials with Bt poplars started in 1994. A first systematic study tried to determine outcrossing into two neighbouring poplar plantations. Hybrids of Bt black poplar and Populus pioner were found at a distance of 500 meters. However, other researchers found much larger outcrossing distances in poplar in Canada. The authors also assume that Bt genes lead to fitness advantages in transgenic poplar and increase the dispersal of transgenic varieties.
The situation in China is problematic in that there have been no published scientific studies on the outcrossing of Bt poplar. Furthermore, there doesn’t seem to be any kind of governmental oversight regarding usage or sale of genetically engineered poplar (such as cuttings).
All poplar species are considered to be trees with a high potential for dispersal, as they are wind pollinated, produce large amounts of pollen, hybridise easily with each other, and proliferate vegetatively by cuttings and root suckers. China is known to be a centre of origin for several poplar species.