CRISPR/Cas9 Applications for Developing Disease-resistant Crop Varieties

Crop diseases caused by fungi, oomycetes, bacteria, viruses and nematodes threaten agricultural productivity and sustainable crop production. Conventional resistance breeding has made important contributions but remains constrained by complex inheritance, limited resistance donors, linkage drag and lengthy breeding cycles. This review examines CRISPR/Cas9 applications for developing disease-resistant crop varieties, focusing on molecular targets, editing strategies, representative crop–pathogen interactions and practical limitations. Principal approaches include disruption of host susceptibility genes, modification of pathogen-responsive promoter elements, editing of host factors exploited by pathogens, manipulation of immune-regulatory pathways and multiplex modification of resistance-associated loci. Examples from rice, wheat, potato, tomato, barley and other crops illustrate the application of these strategies against bacterial, fungal, oomycete and viral diseases. The review also considers precise allele engineering, resistance stacking, CRISPR-mediated transcriptional regulation and emerging Cas12, Cas13, base-editing and prime-editing platforms. Although genome editing offers targeted modification of existing crop genomes, practical application remains constrained by delivery and regeneration difficulties, genotype dependence, unintended genomic alterations, potential fitness penalties and pathogen adaptation. Resistance observed under controlled conditions cannot necessarily be assumed to persist across diverse field environments. Accordingly, CRISPR/Cas technologies are best regarded as complements to conventional breeding. Combining validated molecular targets with careful genomic assessment, pathogen phenotyping and multi-environment evaluation may support the development of more durable and agronomically acceptable disease resistance.