Advances in Durable Resistance to Diseases in Staple Food Crops: A Review

Abstract

Background: At all stages of their development, plants are in permanent contact with causative agents of various diseases. Mechanisms of disease resistance and its durability in crops largely depend on the pathogen’s lifestyle, namely the nutrition mode and host range. Objective: The objective of this review is to consider the main advances in the production of genotypes with durable disease resistance in the globally important food crops, wheat, rice, and potato, as well as barley. Results: In wheat, durable resistance could be provided by the employment of various adult plant resistance genes against biotrophic pathogens, whose action commonly does not involve hypersensitivity response, as well as major quantitative genes, including mutants of susceptibility alleles, against necrotrophs via marker assisted selection (MAS). In barley, the most prominent example is the gene mlo conferring durable powdery mildew resistance, but it is compromised by higher susceptibility to some necrotrophic fungi. A few genes for broad-spectrum resistance against the rice blast and bacterial blight pathogens confirmed their effectiveness for decades, and they could be combined with effective R genes via MAS. Resistance to late blight of potato is mainly provided by R genes introgressed from wild potato species, which could be pyramided with quantitative trait loci. Genes for extreme resistance to potato viruses derived from related species provide durable and broad-spectrum resistance and could be effectively deployed in potato breeding using MAS. Silencing susceptibility genes by genome editing technologies is the most promising approach to produce plants with durable resistance to many pathogens in the crop species. Genetic transformation with genes for resistance-associated proteins or constructs providing silencing via RNA interference is an effective biotechnological method to generate plants with durable resistance against pathogens, especially viruses. Conclusion: Main advances in the production of crop plants with durable resistance are based on studies of molecular mechanisms of plant immunity and its special features for pathogens with different lifestyles via the use of biotechnological approaches such as MAS for pyramiding of monogenic quantitative resistance genes or qualitative R genes, changes in expression of certain genes associated with resistance, the introduction of transgenes, mutagenesis and genome editing aimed at silencing susceptibility genes.