What is disease resistance?
Disease resistance refers to the ability of a plant to limit or withstand the infection and development of pathogens such as fungi, bacteria, viruses, and nematodes that cause disease. There are two main types of disease resistance in plants:
- Passive resistance involves physical or structural barriers that prevent infection or limit parasite growth and reproduction. Examples include waxy layers on leaves, bark on stems, or even production of inhibitors.
- Active resistance relies more on molecular mechanisms that recognize pathogens and mount defensive responses. This induced resistance often involves hypersensitive response (HR) to restrict the spread of infection. HR is characterized by rapid, localized plant cell death around an infection site, which sacrifices a few cells for the overall survival of the plant. Another form of active resistance is systemic acquired resistance (SAR) which protects the whole plant against a broad spectrum of microbes.
There are many benefits to breeding disease-resistant crop varieties:
- Higher and more consistent yields since less crop is lost to disease
- Reduced pesticide usage which is better for the environment and human health
- Lower production costs for farmers due to less need for pesticide sprays
- Prevention of epidemics that could devastate large monocultures
Breeding disease resistance involves identifying genes that confer resistance and introgressing them from wild relatives into elite crop lines using marker-assisted selection or genetic engineering. However, diseases can evolve to overcome resistance over time, so new sources of resistance constantly need to be identified and bred into crops.
Some key points about disease resistance in plants:
- Involves physical or chemical barriers to infection and spread
- Can be passive or active based on defense mechanism
- Resistance genes can be introgressed from wild species
- Reduces crop losses and pesticide usage
- Must be continually updated as pathogens evolve