Question

First, explain the disadvantage of using VOCs as defense signals and then list ways in which the VOCs might provide advantages that outweigh the disadvantages.

Answer 1

Volatile organic compounds (VOCs) are organic chemicals that have a high vapor pressure at ordinary room temperature. Their high vapor pressure results from a low boiling point, which causes large numbers of molecules to evaporate or sublimate from the liquid or solid form of the compound and enter the surrounding air, a trait known as volatility.

There are 10,000+ VOCs chemical compounds and the phenomenon in which escape off the product and enter into the air is known as off gasing.

In plants VOCs play one of the important role

Many plant species have inducible indirect defences against herbivores, emission of volatile organic compounds (VOCs).Moreover, herbivore‐induced VOCs can serve as airborne signals in plant–plant communication, inducing and/or priming defences in undamaged neighbouring plants. However, it remains largely unknown, particularly in woody plants, whether herbivore‐induced VOCs induce and/or prime these two indirect defences simultaneously.

But here the disadvantage is that

antimicrobial activity of VOCs are often performed in Petri dishes by applying pure liquid solution, without even quantifying the real VOC concentration present in the headspace over the course of the experiment. Moreover, while the high biodegradability of VOCs may minimize both their impact and the occurrence of long-term non-targeted effects, at the same time this limits VOC persistence and activity. VOCs are often very reactive with the environment. Reports have demonstrated that VOCs disappear more rapidly in polluted environments where they can react with NOx, OH− radicals, and ozone. Therefore, high reactivity of VOCs limits the distance they travel across the fields and their overall range of protection on crops. Reduction of VOC concentration in air may thus modulate their effect on insects, microbes, and plants. Finally, the very essence of VOCs (volatility) makes these compounds highly influenced by meteorological factors such as wind speed and direction, humidity and rain, and temperature, among others. It is also important to highlight that VOC emissions from leaves in the field can hardly be faithfully reproduced (. In fact, complex blends rather than single VOCs are released by plants, and their biosynthesis is controlled by a network of different biochemical pathways.