TALENs and CRISPR/Cas9 for Rice-Genome Editing

Rice, Oryza sativa L., is an important staple crop that feeds more than half of the world’s population. Cultivated for more than 5,000 years, a huge number of natural and cultivated genotypes exist, representing the richest genetic resource among crop species. Rice also serves as a model species for cereal crops due to its syntenic relationship with other grass species (Gale and Devos, 1998). It was the first crop to have its genome sequenced (Goff et al., 2002; Yu et al., 2002), and the genome sequence of cultivar Nipponbare has been well annotated (Sakai et al., 2013). Rice has been a subject of genetic manipulation by a variety of approaches, including “traditional” mutagenesis (i.e. chemicaland radiationinduced mutation) and forward and reverse genetics. Research in our laboratory has been focusing on host/microbe interactions by using bacterial blight of rice as a model. The pathogen, Xanthomonas oryzae pv. oryzae, causes an important disease in Asia and Western Africa, resulting in severe losses in rice-grain production (Nino-Liu et al., 2006). The objectives of our research include: • identification of virulence factors that facilitate the pathogen’s ability to colonize the host and develop symptoms, • identification of host targets for the pathogen’s virulence factors that cause disease susceptibility, • elucidation of the molecular mechanism of disease susceptibility and resistance mediated by the interactions between the pathogen’s virulence factors and the host’s target genes or gene products, and • engineering resistance based on the best information obtained from study of the disease, an approach that is widely applicable to other related diseases in crops.