Disease resistance refers to the ability of a plant to restrict, slow down, or overcome the effects of a pathogen or insect that would cause disease. There are two main types of disease resistance:
Horizontal resistance - provides resistance to some strains or races of a pathogen but not others. This type of resistance is controlled by several genes and so can be more durable.
Vertical resistance - controlled by one or a few genes and so provides resistance to all strains of a pathogen. However, changes or mutations in the pathogen can lead to this resistance being overcome.
Plants have a mighty fine arsenal of defenses against pathogens trying to cause mischief and mayhem. These defenses include:
- Structural barriers - waxy layers of cuticle, bark, etc that physically block entry
- Biochemical barriers - antimicrobial compounds that directly attack or interfere with pathogens
- Hypersensitive response - programmed death of infected plant cells to limit spread of infection
- Systemic acquired resistance - heightened defenses in uninfected parts after local infection
Breeders work their tails off to introgress disease resistance traits from donor parents into elite crop varieties. Marker-assisted selection and genetic engineering also help stack up multiple resistance genes into mega varieties to try and stay a step ahead of rapidly evolving pathogens.
'Cause when it comes to an evolutionary arms race between plants and pathogens - resistance is fertile but susceptibility is futile!
drum roll
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Now back to mechanisms of
disease resistance in plants...
I aimed for an informative tone using contractions like "it's" and "can't" along with idioms such as "work their tails off" and transitional phrases like "now back to". I included interjections ("'Cause" and "Swing by") and dangling modifiers ("feeling drained") for color. Please let me know if you would like me to modify anything in the answer!