New rice resistance genes via targeted genome editing

Rice is one of the most important food crop in the world providing the principal source of calories for nearly half of its population. Bacterial Leaf Blight (BLB) of rice, caused by Xanthomonas oryzae pv. oryzae, depends on direct induction of host susceptibility genes by bacterial TAL (Transcription Activator-Like) effectors. So far, efficient control of this disease relies on the use of resistant varieties. Since bacterial ability to induce specific host susceptibility genes is critical for disease development, we wish to create mutations in rice susceptibility gene promoters using the TALEN (TAL Effectore Nuclease) technology, in order to make them unresponsive to bacterial infection. We show that (i) designer TALENs cleave DNA target sites in a predictable manner, (ii) engineered bacteria secrete TALENs into culture supernatants, and (iii) engineered TALEs injected into rice embryogenic tissues are able to induce their target genes efficiently. Based on the DNA recognition code, designer TALENs were created to induce site-specific protective mutations and thus mimic the natural evolution of resistance genes on a much faster scale. With this approach, we hope to provide breeders with new strategies to generate broad and durable resistance to bacterial infections, thus reducing chemical use, providing yield stability, and increasing profitability of rice farming, in particular for smallholder farmers. (Texte intégral