Plants can perceive, integrate, and respond to multiple signals and cues informative of imminent threats and opportunities. Here, we tested the hypothesis that unstressed plants are able to perceive and adaptively respond to stress cues emitted from their drought-stressed neighbors and to induce adaptive responses in additional unstressed plants.
Triplets of split-root Stenotaphrum secundatum plants were grown in rows. One root of the first plant was subjected to drought while its other root shared its pot with one of the roots of an unstressed target neighbor, which in turn shared its other pot with an additional unstressed target neighbor.
Cuing from drought-stressed plants increased survival in both proximate directly cued and in more distant relayed-cued target plants under drought. Drought cuing lowered plant performance under benign conditions. Experiments with Wilty mutants and fluridone treatments showed that drought cuing was greatly reduced in ABA-deficient plants.
Our findings demonstrate for the first time the possible adaptive implications of both direct and relayed stress cuing among neighboring plants, the possible cost of plant responsiveness to drought-cues under benign conditions and the involvement of ABA in interplant drought cuing. The results suggest that interplant root communication of drought cues could have novel implications for plant interactions, survival, and performance under both natural and agricultural settings.
