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Description
Plants produce specific volatile organic compounds (VOCs) to protect themselves against biotic and abiotic stresses. When herbivores damage plant tissues, plants release signals, which attract natural enemies of the herbivores and inform neighboring plants about a possible attack. Intensity of plant-herbivore interactions and plant diversity could shape VOC emissions resulting in the production of specific compounds, possibly over different resource availability due to a diverse community. How exactly plant defense mechanisms and diversity influence the VOCs emissions is unknown. We hypothesized that branch-localized VOC emissions after induction are influenced by treatment repetition and tree diversity, ultimately affecting predation rates. To test this, we studied VOCs from Quercus petrea in the MyDiv BEF experiment during leaf flush and predation rates by arthropods using clay caterpillars before, during, and after treatments. We selected oak trees from monocultures, two and four species mixtures. Branches from five oaks per plot were repeatedly treated with methyl jasmonate to simulate herbivory or with water as control. VOCs were passively adsorbed onto PDMS tubes and analyzed by TD-GC-MS. Sesquiterpenes were up-regulated in MeJA-treated branches when compared to control branches, particularly α-Farnesene, known for attracting natural enemies of herbivores. Repeated MeJA treatment intensified branch-localized induction, positively affecting arthropod predation. Green leaf volatile emissions decreased with time in treated branches, possibly due to lower mechanical damage. The interaction between plot diversity and treatment was significant specifically on a green leaf volatile, showing a more intense decrease for the treatment branches on the four-species mixtures plots and a higher up-regulation of Linalool, released as defense against insects. These results show that localized VOCs induction is affected by plot diversity and amplify Q. petraea’s indirect defense potential.
| Status Group | Doctoral Researcher |
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