The ecological implications of interplant drought cuing

Plants are able to perceive, integrate and respond to multiple signals and cues informative of imminent threats and opportunities. Here we studied the ecological implications of interplant drought cuing by subjecting unstressed target plants to short periods of root cuing from neighbors that were either stressed or unstressed by drought. Our findings show for the first time that cues emitted from the roots of drought-inflicted plants could elicit greater survival in neighboring plants under a subsequent drought, yet at the expense of lowered performance under benign conditions. Interestingly, these adaptations and costs could be similarly elicited in immediate neighbors via direct cuing and in more distant neighbors via relayed-cuing. Further investigation into the mechanism of interplant drought cuing implicated abscisic acid (ABA) as the exogenous vector based on three lines of evidence- a) drought cuing was greatly reduced in ABA-deficient plants such as Wilty mutant plants or fluridone-treated plants, b) metabolomic analysis demonstrated that the roots of both drought-stressed plants and their unstressed neighbors exuded significantly more ABA than their uncued controls, c) Both direct and relayed cuing from ABA-treated neighbors increased the survival and performance of unstressed target plants under a subsequent drought, and inflicted performance costs on target plants that grew under benign conditions. were not subjected to a subsequent drought. Our findings suggest that interplant root communication of drought cues could have novel implications for plant interactions, survival and performance under both natural and agricultural settings, calling for its further investigation under field conditions.