Gene flow mitigation by ecological approaches.

Abstract

Abstract With an increased area of cultivating genetically modified (GM) plants worldwide, the ecological risks of transgenic plants released into the environment have caused concern. One of the risks is the occurrence of gene flow between GM plants and non-GM plants, including their wild relatives. Gene flow data from oilseed rape (Brassica napus), cotton (Gossypium hirsutum), maize (Zea mays), soybean (Glycine max), rice (Oryza sativa), and wheat (Triticum aestivum) indicate that the frequency of pollen-mediated gene flow is negatively related with distance between donor and recipient plants, and the frequency is relatively high in closely related species. We discuss five main ecological approaches to mitigate gene flow from GM plants to non-GM plants, including distance isolation, border or trap crops, barrier crops, agricultural practices, and through biological means. The required isolation distance has been adopted in managing GM crops in some countries, and cultivating tall crops, or border or trap crops, can decrease the requisite isolation distance to mitigate gene flow. Combining several approaches is more effective than a single approach in mitigating gene flow, because the frequency of pollen-mediated gene flow depends on plant genotype, flowering time, wind speed and direction, and other factors. Thus, in the framework of biosafety assessment of GM plants, mitigating the occurrence of gene flow between GM and non-GM plants is a key step to decrease the ecological risk of post- commercial cultivation of GM plants.