Disease resistance refers to the ability of a plant to limit the growth and development of a pathogen. There are two main types of disease resistance in plants:
There are major genes that confer strong, race-specific resistance to pathogens with a matching avirulence gene. However, pathogens can evolve to avoid recognition by the resistance gene.
There are also minor genes that confer partial, broad-spectrum resistance. Multiple minor genes provide durable resistance by having an additive effect, but individually they only slow down infections.
Breeding for disease resistance involves identifying good sources of resistance genes in existing germplasm through field screening and crossing them into elite crop varieties by plant breeders. Molecular markers can greatly assist this process through marker-assisted selection.
Some key advantages of genetic disease resistance include:
Many modern crop varieties contain introgressed disease resistance genes from wild crop relatives. This has allowed crops like wheat and potato to remain productive despite emerging virulent races of rust and late blight pathogens.
Staying a step ahead of evolving pathogens is an endless challenge. Using diverse mixtures, pyramiding multiple resistance genes, and continually introgressing new genes through breeding can lead to more durable genetic resistance over time.
Integrating disease-resistant varieties with cultural practices like crop rotation and seed treatments can provide the best overall crop protection strategy. This is essential for global food security to sustainably maximize yields.
So in summary, disease resistance protects plants from pathogens through general and specific defense mechanisms conferred by major and minor resistance genes. Breeding is used to introgress new resistance into crops, but it is an ongoing battle against adapting pathogens. Using resistant varieties as part of an integrated protection strategy is key for sustainable crop productivity into the future.