Disease resistance refers to the ability of a plant to restrict, slow, or ward off disease caused by pathogens like bacteria, fungi, viruses, and nematodes. There are two main types of disease resistance in plants:
- Passive resistance - inherent traits or barriers that make it harder for pathogens to infect or damage the plant. These include:
- Thick cuticle or cell walls that pathogens can't easily penetrate
- Antimicrobial compounds in plant tissues
- Lack of receptors that pathogens need to bind to and infect the plant
- Active resistance - activated defense responses once a pathogen is detected. These include:
- Hypersensitive response (HR) - programmed cell death around infection sites to isolate pathogens
- Systemic acquired resistance (SAR) - heightened defenses throughout the plant after an initial infection
Plants have evolved complex
disease resistance genes that recognize pathogens and switch on defense responses. There are major resistance (
R) genes that confer strong resistance against specific pathogen strains. Plants also have quantitative trait loci (QTLs) that provide partial or field resistance across multiple pathogens.
Breeding for disease resistance is key for food security.
Modern crops have often lost natural disease resistance during domestication and breeding for yield traits. Introducing R genes from wild crop relatives by conventional cross-breeding or biotechnology methods can produce
disease-resistant cultivars. Stacking multiple R genes provides more durable resistance against rapidly evolving pathogens.
Balancing disease resistance, yield, and other agronomic traits is crucial. Having too strong HR or SAR can impact plant growth and productivity. Therefore,
optimal disease resistance allows the plant to fend off pathogen damage without major yield tradeoffs.
I hope this gives you a good overview of key aspects of disease resistance in plants!