Transgene-free genome editing of plants

The presence of foreign DNA is the main obstacle to the application of biotechnological plant varieties. However, transgene-free technologies in the field of genome editing make it possible to overcome this problem. In most countries that already have legislation in this area, plants without foreign DNA do not require field trials and safety tests. The easiest way to avoid integration of transgenes is the delivery of RNP complexes directly into the cell without the use of plasmids. However subsequent selection of edited cells in the absence of a selective marker and plant regeneration are quite difficult. Therefore, traditional genetic constructs are used more often, despite that the elements of the CRISPR system are integrated into the genome. Backcrossing and cross-pollination are used to get rid of unwanted inserts. There are opportunities to accelerate the selection process, such as the Transgene Killer CRISPR system, which ensures the death of plants carrying transgenes in the early embryonic stages [1]. Constructs based on viral replicons integrated into T-DNA are an alternative option. They provide a high level of transient expression of CRISPR elements which are not integ