Bacterial volatile organic compounds as biopesticides, growth promoters and plant-defense elicitors: Current understanding and future scope

Bacteria emit a large number of volatile organic compounds (VOCs) into the environment. VOCs are species-specific and their emission depends on environmental conditions, such as growth medium, pH, temperature, incubation time and interaction with other microorganisms. These VOCs can enhance plant growth, suppress pathogens and act as signaling molecules during plant-microorganism interactions. Some bacterial VOCs have been reported to show strong antimicrobial, nematicidal, pesticidal, plant defense, induced tolerance and plant-growth-promoting activities under controlled conditions. Commonly produced antifungal VOCs include dimethyl trisulfide, dimethyl disulfide, benzothiazole, nonane, decanone and 1-butanol. Species of Bacillus, Pseudomonas, Arthrobacter, Enterobacter and Burkholderia produce plant growth promoting VOCs, such as acetoin and 2,3-bute-nediol. These VOCs affect expression of genes involved in defense and development in plant species (i.e., Ara-bidopsis, tobacco, tomato, potato, millet and maize). VOCs are also implicated in altering pathogenesis-related genes, inducing systemic resistance, modulating plant metabolic pathways and acquiring nutrients. However, detailed mechanisms of action of VOCs need to be further explored. This review summarizes the bioactive VOCs produced by diverse bacterial species as an alternative to agrochemicals, their mechanism of action and chal-lenges for employment of bacterial VOCs for sustainable agricultural practices. Future studies on technological improvements for bacterial VOCs application under greenhouse and open field conditions are warranted.

Automated summary

Bacteria release volatile organic compounds (VOCs) into the environment, which have various effects on plants, including promoting growth, suppressing pathogens, and acting as signaling molecules. Some VOCs also exhibit antimicrobial and pesticidal activities. Different bacterial species produce different VOCs, with some contributing to plant growth promotion. Understanding the mechanisms by which VOCs affect plant genes and metabolic pathways is still a topic of ongoing research.