Disease resistance refers to the ability of a plant to limit the growth and development of a pathogen or insect that could cause disease. There are several types of disease resistance in plants:
- Passive resistance involves physical or chemical barriers that prevent infection, such as waxy layers on leaves, bark on stems and roots, or production of inhibitory chemicals. These barriers are always present and act to exclude or limit pathogens.
- Active resistance relies on the plant recognizing pathogens and mounting defense responses after infection has occurred. This induced resistance often involves a hypersensitive response (HR), wherein plant cells around an infection site rapidly die to limit pathogen spread. Other induced defenses include enzyme activation, structural reinforcements, and antimicrobial compound production.
- Vertical resistance protects plants from specific pathogen strains and is controlled by major host genes that recognize corresponding avirulence genes in the pathogen. This gene-for-gene interaction triggers strong resistance responses.
- Horizontal resistance provides broad-spectrum protection against multiple pathogens and depends on many minor host genes. While less complete than vertical resistance, it is more durable over time.
There are several benefits of disease resistance in plants:
- Reduces crop losses and protects yields
- Lowers grower costs by reducing pesticide needs
- Slows the evolution of new pathogen strains
- Provides environmentally friendly and sustainable disease control
Breeding for enhanced disease resistance is an important goal for plant scientists and growers. Key approaches include conventional breeding to combine resistant traits from different lineages and biotechnological techniques to insert resistance genes. Identifying the genetic basis of resistance and incorporating durable broad-spectrum horizontal resistance are active research areas.
In summary,
disease resistance comprises a range of innate and induced mechanisms in plants that impede infection or limit damage caused by pathogens. Understanding and enhancing these defenses through breeding is critical for developing crops that have maximal, stable yields with minimal agricultural chemical inputs. This promotes productivity and sustainability in the face of evolving disease threats.