Horizontal gene transfer from genetically modified plants - Regulatory considerations

Abstract

Gene technology regulators receive applications seeking permission for the environmental release of genetically modified (GM) plants, many of which possess beneficial traits such as improved production, enhanced nutrition and resistance to drought, pests and diseases. The regulators must assess the risks to human and animal health and to the environment from releasing these GM plants. One such consideration, of many, is the likelihood and potential consequence of the introduced or modified DNA being transferred to other organisms, including people. While such gene transfer is most likely to occur to sexually compatible relatives (vertical gene transfer), horizontal gene transfer (HGT), which is the acquisition of genetic material that has not been inherited from a parent, is also a possibility considered during these assessments. Advances in HGT detection, aided by next generation sequencing, have demonstrated that HGT occurrence may have been previously underestimated. In this review, we provide updated evidence on the likelihood, factors and the barriers for the introduced or modified DNA in GM plants to be horizontally transferred into a variety of recipients. We present the legislation and frameworks the Australian Gene Technology Regulator adheres to with respect to the consideration of risks posed by HGT. Such a perspective may generally be applicable to regulators in other jurisdictions as well as to commercial and research organisations who develop GM plants.

Keywords: GM plants; GMO risk analysis; gene technology regulation; horizontal gene transfer; lateral gene transfer; vertical gene transfer.

FIGURE 1

Summary of matters prescribed in the Australian Gene Technology Regulations 2001 that the Australian Gene Technology Regulator must consider in the risk assessment for a proposal to release a genetically modified (GM) organism, including a (GM) plant, into the environment (OGTR, 2020). Prescribed matters with a background shading of red may include consideration for horizontal gene transfer.

FIGURE 2

A selection of pathways and barriers for the horizontal gene transfer (HGT) from (GM) plants to a selection of recipients. Black arrows indicate direct HGT, grey arrows indicate a secondary HGT event from plant viruses and/or bacterium. [Images courtesy of: (A) canola by Pixabay/Jenő Szabó, (B) Agrobacterium by Jing Xu, Indiana University, (C) Cowpea mosaic virus, PDB ID: 1NY7 (Lin et al., 1999), created using NGL viewer (Rose et al., 2018) at RCSB PDB, (D), (E) and (F) sourced from iStock].