Abstract

Genome Editing in Flax in Response to Environmental Stress

Christopher Cullis, Professor & Chair, Case Western Reserve University

The flax genome can be rapidly modified within a single generation in response to the growth environment. These variations appear to be due to neither random mutations nor the movement of transposable elements, but rather that the genome appears to be able to switch between two well-defined, different sequences at many loci. The identified differences fall into two main classes. One, where regions of the genome have insertions or deletions (indels) among the genotrophs compared to Pl, the second where Pl and the genotrophs have a large number of SNPs over a short region of the genome. Some of the insertions do not exist in an intact form in the progenitor genome. Subsets of these indel variants have been assayed in the progeny from 19 individuals from three different nutrient regimes, from other flax accessions and even the wild progenitor of flax, Linum bienne. In every case the same two alternative structures are seen. What is the source of these variants since they are not present in an intact form in the progenitor genome? Such reproducible large scale variation is unlikely to occur through multiple independent events and therefore an editing mechanism by which long tracts of the genome can be replaced with an alternative structure is being proposed, and the genes controlling this process mapped.