CRISPR-Cas9 and Cas12a (Cpf1) nucleases are two of the most powerful genome
editing tools in plants. Iowa State University researchers compared the
activities of these two nucleases by targeting the maize glossy2 gene coding
region. The research team, led by Keunsub Lee, introduced the SpCas9$B!>(Bguide
RNA (gRNA) and LbCas12a$B!>(BCRISPR RNA (crRNA) into maize inbred embryos using
Agrobacterium$B!>(Bmediated transformation.



Analysis showed that 90-100% of the Cas9$B!>(Bedited T0 plants carried
mutations, 63-77% of which were homozygous or biallelic mutants. Meanwhile,
0-60% of Cas12a-edited T0 plants had the on-target mutations. Analysis of
potential off-target sites for the two nucleases identified 18 and 67
potential off$B!>(Btargets for SpCas9 and LbCas12a, respectively. Further
analysis of the off$B!>(Btarget sites revealed no detectable mutations in the T1
plants.

These results suggest that the CRISPR-Cas9 system used in this study is
highly efficient and specific for genome editing in maize. On the other
hand, CRISPR-Cas12a needs to be improved for genome editing.

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