Improvement of Gene Delivery and Mutation Efficiency in the CRISPR-Cas9 Wheat ( L.) Genomics System via Biolistics.

Discovery of the CRISPR-Cas9 gene editing system revolutionized the field of plant genomics. Despite advantages in the ease of designing gRNA and the low cost of the CRISPR-Cas9 system, there are still hurdles to overcome in low mutation efficiencies, specifically in hexaploid wheat. In conjunction with gene delivery and transformation frequency, the mutation efficiency bottleneck has the potential to slow down advancements in genomic editing of wheat.

The rice blast resistance gene Ptr encodes an atypical protein required for broad-spectrum disease resistance.

Plant resistance genes typically encode proteins with nucleotide binding site-leucine rich repeat (NLR) domains. Here we show that Ptr is an atypical resistance gene encoding a protein with four Armadillo repeats. Ptr is required for broad-spectrum blast resistance mediated by the NLR R gene Pi-ta and by the associated R gene Pi-ta2.

CRISPR/Cas9-Enabled Multiplex Genome Editing and Its Application.

The CRISPR/Cas9 system is a prevalent and versatile genome-editing tool of choice for basic and applied biological research. An exchange of a 20-bp spacer sequence in the gRNA can easily reprogram Cas9 to target a different DNA site. By expressing or providing multiple gRNAs, the system also enables multiplex genome editing at high efficiencies.

Discovery of rice essential genes by characterizing a CRISPR-edited mutation of closely related rice MAP kinase genes.

The clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 nuclease (Cas9) system depends on a guide RNA (gRNA) to specify its target. By efficiently co-expressing multiple gRNAs that target different genomic sites, the polycistronic tRNA-gRNA gene (PTG) strategy enables multiplex gene editing in the family of closely related mitogen-activated protein kinase (MPK) genes in Oryza sativa (rice). In this study, we identified MPK1 and MPK6 (Arabidopsis AtMPK6 and AtMPK4 orthologs, respectively) as essential genes for rice development by finding the preservation of MPK functional alleles and normal phenotypes in CRISPR-edited mutants.

Boosting CRISPR/Cas9 multiplex editing capability with the endogenous tRNA-processing system.

The clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 nuclease (Cas9) system is being harnessed as a powerful tool for genome engineering in basic research, molecular therapy, and crop improvement. This system uses a small guide RNA (gRNA) to direct Cas9 endonuclease to a specific DNA site; thus, its targeting capability is largely constrained by the gRNA-expressing device. In this study, we developed a general strategy to produce numerous gRNAs from a single polycistronic gene.