Airborne signals synchronize the defenses of neighboring plants in response to touch

Plants activate defense-related pathways in response to subtle abiotic or biotic disturbances, changing their vola-tile profile rapidly. How such perturbations reach and potentially affect neighboring plants is less understood. Weevaluated whether brief and light touching had a cascade effect on the profile of volatiles and gene expression of thefocal plant and a neighboring untouched plant. Within minutes after contact,Zea maysshowed an up-regulation ofcertain defense genes and increased the emission of specific volatiles that primed neighboring plants, making themless attractive for aphids. Exposure to volatiles from touched plants activated many of the same defense-relatedgenes in non-touched neighboring plants, demonstrating a transcriptional mirroring effect for expression of genesup-regulated by brief contact. Perception of so-far-overlooked touch-induced volatile organic compounds was ofecological significance as these volatiles are directly involved in plant–plant communication as an effective trigger forrapid defense synchronization among nearby plants. Our findings shed new light on mechanisms of plant responsesto mechanical contact at the molecular level and on the ecological role of induced volatiles as airborne signals inplant–plant interactions