Exploiting Plant Volatile Organic Compounds (VOCs) in Agriculture to Improve Sustainable Defense Strategies and Productivity of Crops

Abstract

There is an urgent need for new sustainable solutions to support agriculture in facing current environmental challenges. In particular, intensification of productivity and food security needs require sustainable exploitation of natural resources and metabolites. Here, we bring the attention to the agronomic potential of volatile organic compounds (VOCs) emitted from leaves, as a natural and eco-friendly solution to defend plants from stresses and to enhance crop production. To date, application of VOCs is often limited to fight herbivores. Here we argue that potential applications of VOCs are much wider, as they can also protect from pathogens and environmental stresses. VOCs prime plant's defense mechanisms for an enhanced resistance/tolerance to the upcoming stress, quench reactive oxygen species (ROS), have potent antimicrobial as well as allelopathic effects, and might be important in regulating plant growth, development, and senescence through interactions with plant hormones. Current limits and drawbacks that may hamper the use of VOCs in open field are analyzed, and solutions for a better exploitation of VOCs in future sustainable agriculture are envisioned.

Keywords: abiotic and biotic stresses; defense priming; smart agriculture; sustainable crop production; volatile organic compounds.

Figure 1

Possible applications of plant VOCs in agriculture: isoprenoids emitted by leaves can exert a protective effect against abiotic stressors by quenching ROS or by strengthening the cell membranes; some VOCs are able to inhibit germination and growth of plant pathogens in vitro; herbivore repellency and attraction of herbivore’s parasitoids on infested plants are probably the most known capacity of VOCs; VOCs can impact on plant defensive system by inducing the synthesis of defense proteins and metabolites (e.g., phytoalexins) that impair microbial colonization; VOCs can also act as priming stimuli by inducing epigenetic changes and accumulation of transcription factors that may facilitate faster expression of plant defenses (a DNA helix is thus shown in the figure), thereby enhancing tolerance or resistance to a future stress episode; VOCs can interact with the mechanism of senescence, or be exploited to fight against unwanted weed species (allelopathic effects).