Green leaf volatiles (GLVs) are a group of volatile organic compounds released by plants when their leaves are damaged or stressed, often as a response to herbivory. These compounds play critical roles in plant communication, signaling neighboring plants to prepare their defenses and attracting natural predators of herbivores. Understanding the biosynthesis and degradation of these compounds sheds light on their function in plant physiology.
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GLVs are primarily synthesized from fatty acids through the lipoxygenase pathway, involving the conversion of linoleic and alpha-linolenic acid.
These compounds not only help in signaling among plants but also have roles in mediating plant-insect interactions, providing a chemical defense mechanism.
Common GLVs include hexenal, (E)-2-alkenal, and green leaf alcohols, which can be emitted within seconds after tissue damage occurs.
The release of GLVs can trigger systemic acquired resistance in neighboring undamaged plants, enhancing their ability to fend off herbivores.
Environmental stressors such as drought or extreme temperatures can influence the quantity and type of GLVs produced by plants.
Review Questions
How do green leaf volatiles function in plant communication and defense mechanisms?
Green leaf volatiles play a crucial role in plant communication by signaling neighboring plants about potential threats like herbivory. When a plant is damaged, it releases these compounds, which can alert nearby plants to activate their own defense mechanisms. This chemical signaling allows for a coordinated response among plants, enhancing their survival against herbivore attacks.
Discuss the biosynthetic pathway of green leaf volatiles and its connection to lipid degradation.
The biosynthesis of green leaf volatiles primarily occurs through the lipoxygenase pathway, where polyunsaturated fatty acids such as linoleic acid are oxidized. This process involves the conversion of membrane lipids into reactive intermediates that ultimately result in the formation of various GLVs. Understanding this pathway highlights the link between lipid degradation and the emission of volatile signals during stress responses in plants.
Evaluate the ecological significance of green leaf volatiles in plant interactions with herbivores and their natural predators.
Green leaf volatiles have significant ecological implications as they not only act as alarm signals for nearby plants but also attract natural predators of herbivores. By releasing GLVs upon damage, plants can indirectly enhance the presence of predatory insects that help control herbivore populations. This interaction creates a dynamic balance within ecosystems, illustrating how plant stress responses can shape community dynamics and influence trophic relationships.
Related terms
Lipid Peroxidation: A process where free radicals attack lipids containing carbon-carbon double bonds, leading to the degradation of cellular membranes and production of volatile compounds.
A large class of organic chemicals derived from terpenes, which can also serve as volatile signals in plants, attracting pollinators or deterring herbivores.
Phytohormones: Plant hormones that regulate growth and responses to environmental stimuli, which can interact with the signaling pathways that lead to the production of GLVs.