Methodology

Poplar is a diploid species - every gene is present in two copies. Using CRISPR/Cas9, we introduced specific changes in both copies of a gene that is crucial for the biosynthesis of lignin. We inactivated one copy and only partially inactivated the other. The resulting poplar line had a stable 10% reduction in lignin amount while it grew normally in the greenhouse. Wood from the engineered trees had an up to 41% increase in processing efficiency. The mutations that were introduced by CRISPR/Cas9 are similar to those that arise naturally. The advantage of the CRISPR/Cas9 method is that the beneficial mutations can be directly introduced into the DNA in only a fraction of the time it used to take.