Establishing a Transgene-free Gene Editing Platform for Bioenergy Crops

Biofuel crops such as Miscanthus and Paulownia have enormous potential to provide economic benefits and greater energy independence to the United States and worldwide, but their utilization is hampered by the absence or insufficiency of key traits, such as biotic and abiotic stress resistance. These limitations hinder their potential as sources of carbon capture and biofuels. When conventional breeding cannot provide trait improvement, gene editing can often be applied, but the lack of transgene-free methods for gene editing in these crops means that the resulting cultivars will be considered Genetically Modified Organisms (GMOs). These GMO cultivars would face regulatory hurdles and an uncertain path to commercialization. Novel transgene-free editing resources for bioenergy crops are needed to remedy this situation. One of the most common methods for genetic modification of plants is via Agrobacterium tumefaciens. Protocols using Agrobacterium are efficient and well established in many crops but usually result in the edited plants having integrated transgenes. This means the resulting cultivars are GMOs. The Gelvin laboratory at Purdue University has developed an Agrobacterium strain that is capable of transient transformation but has a very low rate of transgene integration, allowing it to produce gene-edited plants that are non-GMO. This modified Agrobacterium strain could be used with existing editing methodologies to rapidly deliver non-GMO cultivars. In Phase I, Verinomics will demonstrate the viability of the modified Agrobacterium strain to produce transgene-free non-GMO edited plant regenerants in a model system and lay the groundwork for implementing a full transgene-free editing protocol in Miscanthus and Paulownia. The Gelvin laboratory will incorporate the modifications that enable transgene free editing into additional Agrobacterium strain for use in additional bioenergy crops. In Phase II, we will focus on producing transgene-free, gene edited regenerants of Miscanthus and Paulownia. The editing program will focus on gene targets known to reduce water use and improve drought tolerance to extend their range of cultivation on marginal soils not in competition with food crops. These novel cultivars will serve both as a practical demonstration of the technology and as commercial products. This will bring agriculture to areas of the country that are currently unsuitable and provide new economic opportunities while increasing energy independence and security.