Genetic Engineering and Genome Editing Strategies to Enhance Diseases Resistance of Rice Plants: A Review of Progress and Future Prospects

Abstract

The occurrence of rice diseases threatens food production worldwide. Developing host resistance is considered as the most efficient and environment-friendly method to reduce yield losses due to the diverse group of pathogens. Disease-resistant quantitative trait loci (QTLs) are a valuable resource for rice crop improvement program. Advanced molecular biology and biotechnological tools accelerated the study of host-pathogen interactions and have resulted in the identification, cloning, and characterization of many genes involved in the plant defense responses. The extent of disease reduction varies with the strategy employed as well as with the characteristics of the pathogen. Manipulation of different hormone levels in transgenic rice plants has provided interesting findings with regard to enhanced disease tolerance or susceptibility. The knowledge is being utilized to modify rice genome to develop disease resistance by means of genetic engineering and CRISPR/Cas9-mediated genome editing technologies. Combinatorial effects of more than one defense genes have been proved to be more promising in conferring disease resistance than single-transgene introduction. The use of tissue-specific or pathogen-inducible promoters and the engineered expression of resistant or susceptibility genes that induce defense responses have the potential to provide commercially useful broad-spectrum resistance in the distant future. The issues and challenges of genetic engineering and genome editing to engineer rice disease resistance that need to be addressed are highlighted.