The function of farnesene, a sesquiterpene volatile compound, is multifaceted and plays a crucial role in plant defense mechanisms. It is known to have associations with both insect attraction and the development of superficial scald in apple and pear fruits during cold storage.
1. Plant Defense: Farnesene serves as an essential component of a plant's defense system. When a plant is under attack by insects or pathogens, it releases farnesene into the air as a chemical signal. This volatile compound acts as a pheromone, attracting natural enemies of the attacking insects, such as predatory insects or parasitic wasps. These natural enemies help in controlling the insect population and protecting the plant from further damage.
2. Insect Attraction: Interestingly, farnesene can also attract certain insects, particularly aphids and other herbivorous insects. These insects are attracted to the scent of farnesene, which can act as a feeding stimulant or a signal for suitable host plants. This attraction can be advantageous for the plant as it allows the plant to attract herbivores away from the leaves or other vital parts of the plant, minimizing damage.
3. Superficial Scald: Farnesene is also associated with the development of superficial scald in apple and pear fruits during cold storage. Superficial scald is a browning disorder that affects the skin of these fruits, rendering them unattractive and reducing their market value. Farnesene is believed to play a role in the synthesis of alpha-farnesene oxidation products, which are responsible for the development of scald symptoms. The exact mechanism is still not fully understood, but it is thought that the oxidation products may cause membrane damage, leading to the browning of the fruit skin.
Personal Experience: As a sommelier and brewer, I have encountered farnesene in the context of brewing hoppy beers. Hops, an essential ingredient in brewing beer, contain various volatile compounds, including farnesene. Farnesene contributes to the aroma and flavor profile of hoppy beers, adding a distinct herbal and woody character. Its presence in hops is desirable for certain beer styles, such as India Pale Ales (IPAs), where a pronounced hop aroma is sought after.
The function of farnesene is diverse and complex. It serves as a chemical signal for both plant defense and insect attraction. While it can attract natural enemies of insects, it can also lure herbivores away from vital plant parts. Additionally, farnesene's involvement in the development of superficial scald in apple and pear fruits during cold storage highlights its role in fruit physiology. Understanding the function of farnesene is crucial for exploring its potential applications in agriculture, pest management, and even the brewing industry.