Researchers have been using the CRISPR-Cas9 system to edit the genomes of
important crops such as wheat. Despite the tractability in designing this
system, the efficacy of the tool is also dependent on the DNA delivery
method. The most common delivery method is biolistics based transformation
but due to the high frequency of gene silencing linked with high copy
transgenes and low edit rate in wheat, a large population of transgenic
plants are needed for recovery of desired mutations. This led Zhengzhi Zhang
from the University of Missouri and team to develop an
Agrobacterium-delivered CRISPR-Cas9 system in wheat.



The reported system includes a wheat codon optimized Cas9 driven by a maize
ubiquitin gene promoter and a guide RNA cassette driven by wheat U6
promoters in a single binary vector. Using the system, they have developed
69 edit mutants for four grain-regulatory genes in three generations at an
average edit rate of 10% without detecting off-target mutations in the most
Cas9-active plants.

Based on the positive results of the study, it has proven that the
Agrobacterium-delivered CRISPR-Cas9 system could be used for wheat genome
editing, which only needs a small number of transformation events.



[onlinelibrary.wiley.com]