Talen and Crispr-Cas9 Induced Genetic Variations for Plant Disease Resistance.

Modified CRISPR (clustered regularly interspaced short palindromic repeats) systems, comprising single guide RNAs (sgRNAs) and Cas9 endonucleases, and TALENs, fusion proteins of TAL effectors and the FokI endonuclease domain, have emerged as potent biotechnological tools for both basic and applied research. The most promising utilization of both Cas9/sgRNA and TALENs is for targeted genome editing, precise genetic alterations within any genome of interest, as demonstrated in a plethora of organisms including several crop plants. My presentation describes development and application of these two technologies to generate heritable genome modifications in rice. TALENs were employed to generate stable, heritable mutations in dozens of rice genes. The frequency of mutagenesis varied from species and constructs targeting different genes. The highest rate in rice reached about 65% of transgenic lines carry desired mutations. Phenotypic changes associated with mutated genes were observed in some mutant lines in rice. We also modified the Cas9/sgRNA system suitable for targeted gene mutagenesis in rice. The two systems have been successfully applied to rice for targeted mutagenesis of many genes.  Transgenic lines of T0 generation carrying site-specific mutations were produced at frequency as high as 100% in rice. I will also present examples that TALEN-mediated promoter mutations lead to disease resistance to bacterial blight in the otherwise susceptible rice cultivars. Our results demonstrate that TALENs and Cas9/sgRNA are effective toolboxes for genome editing in rice, empowering the discovery of gene function and the trait improvement.