Gene Editing With TALEN and CRISPR/Cas in Rice

Engineered, site-specific nucleases induce genomic double-strand DNA breaks and break repair processes enable genome editing in a plethora of eukaryotic genomes. TALENs (transcription activator-like effector nucleases)and CRISPR/Cas (clustered regularly interspaced short palindromic repeats and CRISPR-associated proteins)are potent biotechnological tools used for genome editing. In rice, species-tailored editing tools have proven to be efficient and easy to use. Both tools are capable of generating DNA double-strand breaks (DSBs)in vivo and such breaks can be repaired either by error-prone NHEJ (nonhomologous end joining)that leads to nucleotide insertions or deletions or by HDR (homology-directed repair)if an appropriate exogenous DNA template is provided. NHEJ repair often results in gene knockout, while HDR results in precise nucleotide sequence or gene replacement. In this review, we revisit the molecular mechanisms underlying DSB repair in eukaryotes and review the TALEN and CRISPR technologies (CRISPR/Cas9, CRISPR/Cpf1, and Base Editor)developed and utilized for genome editing by scientists in rice community.