Disease resistance - Balance Hormone Center

What is disease resistance?

Disease resistance refers to the ability of a plant to prevent, restrict, or reduce the effects of a pathogen. It is an important concept in agriculture and crop breeding. There are two main types of disease resistance in plants:

• Vertical resistance - This refers to resistance that is effective against specific races or strains of a pathogen. It is controlled by single genes and is often race-specific. An example is a wheat variety carrying a gene that makes it resistant to a particular race of the stem rust fungus.
• Horizontal resistance - This type provides resistance against multiple strains or races of a pathogen. It is controlled by multiple genes and is non-specific. An example is partial resistance in wheat to the leaf rust fungus, controlled by several minor genes.

Plants have developed complex physical and chemical defense systems against pathogens over the course of evolution. These defense mechanisms are manifested as disease resistance. Some key examples include:

• Structural defenses like thick cell walls, waxy layers on leaves, and bark on stems. These act as physical barriers to block pathogen entry.
• Antimicrobial compounds like phenols, phytoalexins, pathogenesis-related (PR) proteins that inhibit microbial growth.
• Hypersensitive response involving programmed cell death around infection sites to restrict pathogen spread.

There are several benefits of disease resistance in crops:

• Higher and stable yields as the crop is protected from disease even if inoculum is present.
• Reduced need for pesticides, making cultivation eco-friendly and safer.
• Lower costs of cultivation due to savings on chemical sprays.

Strategies used to incorporate disease resistance in crops include introduction of resistance genes from cross-compatible species through breeding, mutation breeding, transgenic techniques, and marker-assisted selection.