What is disease resistance?
Disease resistance refers to the ability of a plant to limit the growth and development of a pathogen that could otherwise cause disease. There are several types of disease resistance in plants:
- Passive resistance involves physical or structural barriers that prevent infection in the first place, like waxy layers on leaves that block pathogens from entering.
- Active resistance relies on the plant recognizing pathogens and mounting defense responses to stop an infection. This can include:
- Hypersensitive response (HR) - programmed plant cell death at infection sites, stopping the spread of pathogens
- Systemic acquired resistance (SAR) - whole-plant defenses activated after an initial infection that provide long-term protection against a broad spectrum of pathogens
- Non-host resistance means that most varieties of a plant species are resistant to a particular pathogen due to incompatibility between the plant and pathogen.
There are a few main ways that plants develop disease resistance:
- Some forms of resistance are inherent to the plant variety or species based on innate genetic factors that block infection or limit pathogen growth.
- Other types of resistance come from specific R genes that recognize and initiate defenses against pathogens with matching "avirulence" genes. This gene-for-gene interaction leads to an incompatible interaction that stops infection.
- Resistance can also be acquired by exposing plants to certain hormones, chemicals, or weakened pathogen strains that activate systemic defense pathways like SAR and prime them for enhanced future resistance.
Breeding disease-resistant crop varieties is crucial for developing sustainable and productive agricultural systems. Understanding the genetic basis of resistance helps guide breeding programs to select for key resistance traits and genes. Identifying new sources of genetic resistance also provides plant breeders with raw material to continue improving commercial varieties.
In summary, plants have a diversity of physical, chemical, and genetic factors that confer disease resistance and limit losses from major pathogens. Understanding different forms of resistance is key for developing integrated disease management strategies.