Genome editing interventions to combat rice blast disease

Abstract

Rice is the major food crop of the world. Production of rice is threatened by a number of biotic and abiotic stresses and these could result in a significant yield reduction, sometimes up to 60–100%. In addressing losses to emerging diseases, development of resistance to blast, sheath blight, and false smut is the need of the hour. The traditional approach of using resistance R genes for building sustainable resistance is not viable anymore due to continuously evolving strain of pathogens, thus causing intransigence erosion. The contemporary intervention strategy of identifying and precisely mutating susceptibility genes opens up new vistas for exploiting susceptible genes. Approaches like mutation breeding and transgenic held good promise to further yield increases in rice and provide protection against disease induced yield losses. However, all these approaches either proved inadequate over time or faced regulatory hurdles and were successful to a limited point. Recently, a new genome editing (GE) approach has offered a promising alternative to develop unique alleles in a shorter time frame without linkage drag. Thus, the present review highlights various R, non-R (S) gene choices amenable for genome editing, compared with available conventional breeding approaches, like wide-hybridisation using wild relatives, including new genetic resources. Hence, a range of breeding resources can be employed by crop breeders to assemble disease resistance against emerging diseases of rice. Many successful examples on disease resistance are collated from recently published work. It is hoped that creating new allelic series of variants would be a practical and sustainable solution to address the challenges posed to food security.