Disease resistance - Rejuvenate Clinic

What is Disease Resistance?

Disease resistance refers to the ability of a plant to restrict, retard, or overcome the effects of a pathogen or disease. It involves a complex set of defense mechanisms that have evolved in plants to recognize and respond to pathogens attempting to infect and damage tissues.

There are two main types of disease resistance in plants:

• Passive resistance - involves physical and chemical barriers such as waxy layers on leaves, bark on stems, or anti-microbial chemicals that hinder the growth and spread of pathogens. These barriers are always present and provide the first line of defense.
• Active resistance - involves immune responses triggered by the plant when it recognizes disease-causing microbes. This resistance is more specific, stronger, and provides lasting protection to the plant from diseases.

Active resistance can be further divided into two categories:

1. Nonhost resistance - provides resistance to all genetic variants of a pathogen. For example, all maize lines resist the wheat rust pathogen due to nonhost resistance.

2. Host resistance - provides resistance to some variants of a pathogen. This resistance operates through distinct mechanisms:

• Qualitative resistance - controlled by R genes and provides strong resistance against some pathogen races. It is either present or absent - no intermediate forms.
• Quantitative resistance - controlled by multiple genes and provides partial resistance against all genetic variants of a pathogen. It varies in degree - from slight to high.

Researchers are continually identifying new sources of genetic disease resistance from diverse germplasm and relatives of cultivated crops. These resistance genes are introduced into elite crop varieties using plant breeding techniques, providing environmentally safe and durable disease control solutions for sustainable agriculture.