Green leaf volatiles

Green Leaf Volatiles (GLVs) are a group of volatile organic compounds (VOCs) that are released by plants when they are damaged or stressed. These compounds are responsible for the characteristic "green" odor associated with freshly cut grass or damaged leaves. GLVs play a significant role in plant biology, including serving as signals for plant-to-plant communication and in the attraction of predatory insects that feed on herbivores attacking the plants.

Production and Composition

GLVs are produced through the lipid peroxidation of polyunsaturated fatty acids. This process is initiated by the action of enzymes such as lipoxygenase (LOX) following physical damage to plant tissues. The primary components of GLVs include six-carbon aldehydes, alcohols, and their esters, such as hexanal, (Z)-3-hexenal, (E)-2-hexenal, hexanol, and (Z)-3-hexenol. Among these, (Z)-3-hexenal is particularly notable for its potent green odor.

Biological Functions

GLVs have several important biological functions:

Defense Mechanism

GLVs can act as direct defense mechanisms against herbivores by deterring their feeding. Some GLVs are toxic or repellant to certain insects, reducing the likelihood of further damage to the plant.

Signaling

GLVs also serve as indirect defense mechanisms by signaling the presence of herbivores to predatory insects and mites, which then prey upon the herbivores. This signaling can occur both within a single plant and between plants, alerting neighboring plants to the threat and triggering their own defensive responses.

Stress Response

The release of GLVs is part of the plant's stress response mechanism. Apart from herbivore attack, GLVs can be released in response to other stress factors such as mechanical damage, pathogen infection, and abiotic stresses.

Ecological Impact

GLVs play a significant role in the ecosystem by mediating interactions between plants and insects, including pollinators and herbivores, as well as between plants themselves. They contribute to the complexity of plant communities and biodiversity by influencing plant competition, herbivory, and predation patterns.

Research and Applications

Research on GLVs has implications for agriculture, pest management, and the study of plant ecology and evolution. Understanding the role of GLVs in plant defense can lead to the development of crop protection strategies that exploit natural plant defenses, reducing the need for chemical pesticides.