Disease resistance refers to the ability of a plant to restrict, slow down, or overcome the effects of a pathogen. It is an important concept in agriculture and crop breeding. There are two main types of disease resistance:
- Vertical (specific) resistance - protects the plant from specific pathogen strains. It is controlled by a gene-for-gene interaction, where a resistance (R) gene in the plant matches with a corresponding avirulence (Avr) gene in the pathogen. This interaction triggers strong defense responses in the plant.
- Horizontal (broad-spectrum) resistance - provides protection against multiple pathogen strains/races. It is generally controlled by multiple genes and is more durable over time.
Plants have
innate and adaptive immune systems to defend themselves. Innate immunity provides basal protection through physical and chemical barriers. Adaptive immunity involves R genes and defense signaling pathways. Plants may exhibit
antibiosis (inhibiting pathogen growth) or
tolerance (growing well despite infection).
Breeders introgress different R genes into crop varieties to develop disease resistant cultivars. However, pathogens can evolve to overcome R genes. Therefore, gene
pyramiding (stacking multiple R genes) is commonly used for more durable resistance. Integrated disease management with mixed approaches is ideal.
Marker-assisted selection now enables rapid and targeted introgression of resistance traits during plant breeding, by tracking DNA markers linked to resistance genes. This is more efficient than purely phenotypic selection. Popular examples include bacterial blight resistance in rice and rust resistance in wheat. Climate change is reducing disease resistance in some varieties, posing new breeding challenges.
In summary, disease resistance protects plants from pathogens, through specific or broad-spectrum interactions, aided by molecular markers. A blend of genetic resistance and integrated disease management is ideal for sustainable agriculture. Reach out to
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