Plant's defence mechanisms against pathogens

Many Volatile Organic Compounds (VOCs) are known to cause harm to human health and the environment. However, there is a subset of VOCs that are proved to be useful in growing and maintaining the health of plants.

This subset is called Green Leaf Volatiles (GLVs). This group of compounds is found mostly in green plants and is released when these plants respond to external stress factors. These stressors can be either abiotic or biotic, or a combination of both. Stress factors include but aren’t limited to herbivore consumption, agriculture, and adverse weather. These stressors trigger a response in plants which is to emit organic compounds such as aldehydes and esters.

Many of the crops we raise on a large scale and for consumption actually depend on GLVs for their survival and fitness. One example is the tobacco crop. When an insect herbivore attempts to feast on the leaves of the tobacco plant, the plant will quickly release GLVs.

The plant releases those GLVs to dispose of the herbivores. The GLVs act as a signal to predators about the presence of those insects that feast on the plant’s leaves. The result is that the plant naturally gets rid of the herbivores. These compounds act as an evolutionary means of pest control and herbivore defense.

Aside from getting rid of the organisms that feed on the plant’s leaves, GLVs can also influence the plant’s defense response against pathogens. Some GLVs help inhibit the growth of viruses, bacteria, and fungi. For example, fungicidal activity was detected in Arabidopsi thaliana plants when they accumulated GLVs (and interacted with other substances) as a response to a previous infection.

In summary, plants release substances such as GLVs that naturally protect them from pests and pathogens. If scientists can manipulate or modify the key pathways, we can enable plants to produce their own natural pesticides, herbicides, and antimicrobials. This means reduced costs and less reliance on toxic sprays. This also means we can produce natural foods with improved quality.