Genome Editing in Forest Trees

Since the first CRISPR/Cas-mediated genome editing of poplar in 2015, an increasing number of tree species are being genome-edited. Although the availability of genome sequences, tissue culture and transformation systems are limiting factors, research is ongoing on advanced methods such as DNA-free genome editing and gene targeting approaches in addition to the optimisation of single gene knockouts. These can be used to address ambitious issues and perform genome editing more accurately, which has implications for the legal assessment of edited trees. Once technically established, CRISPR/Cas can be used to circumvent specific challenges related to forest tree species, e.g., longevity and extended vegetative phases, and to modify traits relevant for breeding, whether for direct application or to elucidate the genetic basis of individual traits. Not least due to climate change, adaptation to abiotic stress such as drought stress as well as biotic stresses caused by pathogens are strongly in focus. For the use as a renewable resource and as a carbon sink, wood productivity in forest trees as well as wood properties are of interest. In biosafety assessments, tree-specific aspects have to be considered, which result, among other aspects, from the long lifespan.