2011 Volume 28 Issue 2 Pages 251-261
The release of genetically modified plants into the environment can only occur after permission is obtained from the relevant regulatory authorities. This permission will only be obtained after extensive risk assessment shows comparable risk of impact to the environment and biodiversity as compared to non-transgenic host plants. Two transgenic rose (Rosa×hybrida) lines, whose flowers were modified to a bluer colour as a result of accumulation of delphinidin-based anthocyanins, have been trialed in greenhouses and the field in both Japan and Australia. Flower colour modification was due to expression of genes of a viola flavonoid 3′,5′-hydroxylase and a torenia anthocyanin 5-acyltransferase. In all trials it was shown that the performance of the two transgenic lines, as measured by their growth characters, was comparable to the host untransformed variety. Biological assay showed that the transgenic lines did not produce allelopathic compounds. In Japan, seeds from wild rose species that had grown in close proximity to the transgenic roses did not carry either a Rosa×hybrida specific marker gene or the transgenes. In hybridization experiments using transgenic rose pollen and wild rose female parents, the transgenes were not detected in the seed obtained, though there was a low frequency of seed set. The transgene was also not transmitted when Rosa×hybrida cultivars were used as females. In in situ hybridization analysis transgene transcripts were only detected in the epidermal cells in the petals of the transgenic roses. In combination, the breeding and in situ analysis results show that the transgenic roses contain the transgene only in the L1 layer cells and not in the L2 layer cells that generate reproductive cells. General release permissions have been granted for both transgenic lines in Japan and one is now commercially produced.