Environmental microbes as modulators of plant volatile landscapes: Implications for plant–insect chemical communication
Zhang et al., 2026
Free-living environmental microbes at four plant-atmosphere interfaces (leaf, nectar, fruit, and bark surfaces) intercept, biotransform, and augment plant volatile signals, shaping what herbivores, pollinators, and parasitoids detect. This forum article reviews how microbes remodel these signals, the threats posed by climate change and land-use intensification, and priorities for translating microbial volatile ecology into sustainable pest management.
The global phyllosphere spans an estimated 1 billion square kilometres of above-ground plant surface, placing surface-dwelling epiphytes, carposphere colonisers, and nectar inhabitants at the plant-atmosphere boundary. At the plant-atmosphere interface, these microbes occupy a biochemical gatekeeper role: intercepting, consuming, and transforming plant-emitted volatile organic compounds (VOCs) before those signals reach insect receivers. Isoprene monooxygenases in Rhodococcus and Variovorax catalyse the oxidation and biocapture of isoprene emitted from leaf surfaces, while fungal cytochrome P450 monooxygenases, reductases, and Baeyer–Villiger oxidases execute stereoselective biotransformations, including regioselective hydroxylation of inactivated C–-H bonds, enantioselective carbonyl reduction, and lactone-forming oxidations.
Biotransformation can redirect a plant monoterpene into functionally divergent chemical spaces. For example, Aspergillus niger DSM 821 and Corynespora cassiicola DSM 62475 can convert (±)-linalool into furanoid and pyranoid linalool oxides, while A. niger DSM 821 and Botrytis cinerea additionally produce lilac aldehydes and lilac alcohols as byproducts through a pathway postulated to proceed via 8-hydroxylinalool. Furanoid linalool oxide is electroantennographically active in bee pollinators and attracts hoverflies, while lilac aldehyde acts as a repellent to the same hoverfly species. Thus, fungal biotransformations can generate compounds with opposing semiochemical functions within the same receiver community. Plant VOCs, in turn, shape phyllosphere microbial community composition, establishing bidirectional exchanges with direct consequences for herbivore, pollinator, and parasitoid perception.
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