Abstract
Transgenic woody plants have been rapidly developed in recent years, and the commercial use of these transgenic plants has been recognized as an important approach to solving environmental and food problems. Concomitantly, the potential impact of transgenic woody plants on peripheral ecosystems should be considered before they are released for practical commercial use. In this study, we have used environmental biosafety assessments to evaluate three lines of transgenic Eucalyptus globulus that harbor the choline oxidase (codA) gene and have previously been proven to have different levels of salt tolerance. The assessments included two allelopathy bioassays and a survey on rhizosphere microbes, which have shown practicability in other transgenic plants. The two allelopathy bioassays were used for evaluating the potential impact of the transformants on the surrounding vegetation. The survey on rhizosphere microbes was performed to investigate the potential impact of transformants on the rhizosphere microbe community. The results indicated there was no significant difference between the transformants and non-transformants with respect to the impact on the surrounding vegetation and the rhizosphere microbe community. A combination of our biological evaluation of E. globulus was then used to successfully obtain approval for the plantation of transgenic E. globulus in a Type I field trial in Tsukuba.
