Creation of gene-specific rice mutants by AvrXa23-based TALENs

Transcription activator-like effector (TALE) nucleases (TALENs) are increasingly used as a powerful tool for genome editing in a variety of organisms. We have previously cloned the TALE-coding gene avrXa23 from Xanthomonas oryzae pv. oryzae and developed an AvrXa23-based assembly system for designer TALEs or TALENs. Here, we exploit TALENs to induce mutagenesis of the rice ethylene response factor (ERF) transcription factor OsERF922 for testing the gene-editing efficiency of AvrXa23-based TALENs system. A pair of TALENs (T-KJ9/KJ10) was assembled and their nuclease activities were first confirmed in rice protoplast transient assay. The TALENs-expressing construct pT-KJ9/KJ10 was then used for rice transformation. We observed targeting somatic mutagenesis frequency of 15.0% in positive transgenic rice calli and obtained two mutant plants with nucleotide deletion or insertion at the designer target region. Our work demonstrates that the AvrXa23-based TALENs system can be used for site-specific genome editing in rice.