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1. Half Earth- there is only a short 2 sentence description of the book, needs more detail about contents/author
2. Green leaf volatiles- lacking examples of green leaf volatiles and info on what purpose they serve in plants
3. Epibionts- needs examples and info on why they are important to ecosystems/why some species require this for survival
4. european ecological federation- only lists the members, lacks info on what the federation does, when it began and what projects it has already completed

When a plant suffers tissue damage from herbivores or pathogens, it will rapidly begin producing much greater numbers of GLVs in just seconds.

Green leaf volatiles (commonly abbreviated as GLV) are volatile organic compounds that are released when plants suffer tissue damage. Specifically, they include aldehydes, esters, and alcohols of 6-carbon compounds released after wounding. These compounds are very quickly produced and emitted, and are used by nearly every green plant. Plants constantly release GLVs, but un-stressed plants release them in much smaller amounts. Some of these chemicals act as signaling compounds between either plants of the same species, of other species, or even vastly different lifeforms like insects. GLVs also have antimicrobial properties to prevent infection at the site of injury. Some, although not necessarily all, of these chemicals act essentially as plant pheromones.^[12]

Uses

GLVs are used in both plant-plant and plant-insect interactions. They usually serve as a warning signal of oncoming causes of tissue damage. When a plant is attacked, it emits GLVs into the environment through the air. Undamaged neighboring plants perceive these GLV signals and activate the expression of genes related to the plants defense mechanisms. This allows the plant emitting the GLVs and the neighboring plants to enter a primed state. In this primed state plants activate their defenses systems more quickly and in a stronger concentration. The amount of GLVs that a wounded plant emits is directly related to the severity of the injury, so the concentration of GLVs in the atmosphere and the frequency of exposure both play a role in neighboring plants successfully entering a primed state.

In plant-insect interactions, GLVs are used as a form of defense. They alert predators to the locations of herbivores that are preying on the plant and causing tissue damage. For example, a study done by Northwestern University found that parasitic wasps are more attracted to plants that are emitting GLVs due to wounding from herbivores than to plants that are emitting GLVs due to mechanical damage. In order to determine if plants are capable of recognizing and distinguishing between GLVs, a study was done at University of California Davis where researchers exposed plants to GLVs emitted by a mechanically damaged tomato plant, and to GLVs emitted by a tomato plant that had been damaged by herbivores. Researchers observed a difference in the plants reaction, showing an increase in the proteins related to defense mechanisms for the plant exposed to the herbivore GLVs. This supports the theory that plants are able to distinguish between different GLVs, and react differently depending on which signal they receive.

Antimicrobial Properties

Other benefits of Green Leaf Volatiles are that at the site of damage, GLVs are released in high concentrations and act as antimicrobial agents to make the plant more resistant to bacterial or fungal infections. To study the anti-fungal properties of GLVs, researchers at the University of Arizona influenced how plants expressed HPL, the main enzyme of GLV synthesis. Scientists compared the rates of fungal spore growth in HPL over-expressing and HPL silencing mutants to the wild type plants. Results from the study showed lower rates of fungal growth and higher GLV emissions on the HPL over-expressing mutants, while the HPL silencing mutants showed higher rates of fungal growth and lower GLV emissions, which supports the hypothesis that GLVs have antimicrobial properties.

The antimicrobial properties of GLVs have also been part of an evolutionary arms race that raise questions for scientists. During an infection, plants emit GLVs to act as microbial agents, but bacteria and viruses have adapted to use these GLVs to their own benefit. The most common example of this is found in the red raspberry. When the red raspberry plant is infected, the virus influences it to produce more GLVs, which attract the red raspberry aphid. These GLVs cause more aphids to come and to feed on the plant for longer, giving the virus better chances of being ingested and spread more widely. Researchers are now trying to determine whether under infectious conditions plants emit GLVs for their benefit, or if bacteria and viruses induce the release of these compounds for their own benefit. Studies in this area have been inconclusive and contradictory.

Pathway for biosynthesis of the GLV cis-3-hexenal from linolenic acid. The first step involves formation of the hydroperoxide by the action of a lipoxygenase. Subsequently a hydroperoxide lyase induces formation of the hemiacetal, the precursor to a volatile C6 compound.