From Radiation to Precision: A Review of Physical, Chemical, and Site-Directed Mutagenesis in Resistance Against Plant Diseases

The increasing demand for resilient, high-yielding crops has intensified the need for effective strategies to combat biotic stresses and reduce reliance on costly and environmentally detrimental chemical controls. Mutagenesis, through physical, chemical, and site-directed approaches, complements conventional breeding by accelerating the discovery of genes and their functional characterization. This review examines the application of mutagenesis in major crop species, with particular emphasis on disease resistance research and the dissection of plant–pathogen interactions. Although relatively few mutagenized disease resistance alleles have been directly deployed to date, we highlight how mutagenesis has advanced the identification and validation of major genes controlling plant immunity, particularly susceptibility genes against a wide range of diseases, from viruses and bacteria to fungi with diverse lifestyles. A prominent example is the development of durable mlo -mediated resistance to powdery mildew, from its discovery through X-ray mutagenesis in barley to targeted editing of mlo homologs in polyploid crops. The range of plant immunity genes identified by researchers and growing regulatory approval of gene editing as an alternative to GMOs suggest accelerating adoption of the technology.