Disease Resistance Overview
Disease resistance refers to the ability of a plant or animal to prevent or limit infection by a pathogen such as a virus, bacteria, or fungus. There are several types of disease resistance:
- Vertical Resistance - Resistance that protects against specific pathogen strains or races. This resistance is controlled by R genes and is usually race-specific.
- Horizontal Resistance - Resistance that provides partial protection against all races of a pathogen. This form of resistance is more durable over time.
- Induced Resistance - Resistance triggered by external factors. For example, some chemicals can switch on plant defense mechanisms against pathogens.
Plants have physical and chemical barriers to block pathogen invasion, as well as R genes that recognize specific pathogens and trigger defense responses. Common defenses include:
- Cell Wall Thickening to block entry
- Antimicrobial Compound Production to kill pathogens
- Hypersensitive Response that isolates infection sites
Breeding for disease resistance aims to introduce R genes from wild relatives into cultivated varieties. Other strategies include gene editing techniques like CRISPR to disable susceptibility genes.