Environmental biosafety assessment on transgenic Oncidium orchid modified by RNA interference of Phytoene Synthase genes.

Hybrid Oncidium orchids, such as Oncidium Gower Ramsey and Oncidium "Honey Angel," are popular cut flowers in Japan and Taiwan. Due to pollen sterility, no new varieties have been created by conventional breeding methods. Recently, we employed RNA interference (RNAi) technology to suppress phytoene synthase and successfully modified floret hue from yellow to white (Liu et al. 2019). Transgenic white Oncidium orchids, Honey Snow MF-1, have been grown to test their genetic stability, and their environmental biosafety was assessed for approximately one year under government regulatory instructions from the Council of Agriculture, Taiwan. In the present study, pollen sterility was demonstrated by cytological observation of the microsporogenesis step, pollen morphology abortion, and failure of pollen germination. Assays on allelopathic effect on the other plants and the soil rhizospheric microbial flora-revealed that transgenic Oncidium orchids are potentially safe with regard to environmental biodiversity. Therefore, the general release permissions have been granted and an application for licensing for commercial production is under way.