Dialogue between jasmonic acid and phyllosphere microorganisms enhanced tomato defense against Helicoverpa armigera larvae

BACKGROUND: Phyllosphere microorganisms play a vital role in plant defense, thereby aiding plants in their adaptation to environmental changes. Plant hormone signals can regulate the composition of the phyllosphere microbial community. Jasmonic acid (JA) is a critical phytohormone that regulates anti-herbivore pathways in plants; however, the dialogue between JA and phyllosphere microorganisms in anti-herbivore defense remains unclear. Here, we investigate the role of JA-enriched phyllosphere microorganisms in the defense of tomato plants against Helicoverpa armigera Hübner. RESULTS: Our results demonstrate that JA-enriched phyllosphere bacteria enhance the direct defense of tomato plants by inhibiting the development of H. armigera larvae. Furthermore, these microorganisms increase the plants' ability to attract predatory Harmonia axyridis Pallas by elevating the emission of specific volatile organic compounds (VOCs) namely α-pinene, α-terpinene, and caryophyllene. We observed positive correlations between the abundance of phyllosphere microorganisms, the level of VOC emissions, and the density of trichomes, suggesting an integrated anti-herbivore defense network regulated by JA. CONCLUSION: These findings underscore the importance of phyllosphere microorganisms in enhancing plant fitness and further comprehension of the intricate relationship between plant anti-herbivore defenses and phyllosphere microorganisms. © 2026 Society of Chemical Industry.