Rumor Has It…: Relay Communication of Stress Cues in Plants

Omer Falik,Aaron Fait,Lydia Quansah,Yonat Mordoch,Ariel Novoplansky,Juergen Kroymann

doi:10.1371/journal.pone.0023625

Abstract

Recent evidence demonstrates that plants are able not only to perceive and adaptively respond to external information but also to anticipate forthcoming hazards and stresses. Here, we tested the hypothesis that unstressed plants are able to respond to stress cues emitted from their abiotically-stressed neighbors and in turn induce stress responses in additional unstressed plants located further away from the stressed plants. Pisum sativum plants were subjected to drought while neighboring rows of five unstressed plants on both sides, with which they could exchange different cue combinations. On one side, the stressed plant and its unstressed neighbors did not share their rooting volumes (UNSHARED) and thus were limited to shoot communication. On its other side, the stressed plant shared one of its rooting volumes with its nearest unstressed neighbor and all plants shared their rooting volumes with their immediate neighbors (SHARED), allowing both root and shoot communication. Fifteen minutes following drought induction, significant stomatal closure was observed in both the stressed plants and their nearest unstressed SHARED neighbors, and within one hour, all SHARED neighbors closed their stomata. Stomatal closure was not observed in the UNSHARED neighbors. The results demonstrate that unstressed plants are able to perceive and respond to stress cues emitted by the roots of their drought-stressed neighbors and, via ‘relay cuing’, elicit stress responses in further unstressed plants. Further work is underway to study the underlying mechanisms of this new mode of plant communication and its possible adaptive implications for the anticipation of forthcoming abiotic stresses by plants.

Highlights

Signal perception, learning and decision-making abilities are usually thought to rely on sophisticated central nervous systems (CNS); information acquisition and communication are ubiquitous even among the oldest and most rudimentary life forms [1,2,3,4]
Fifteen minutes following water injection to the unshared rooting volume of the IND plant, stomatal width of all plants decreased by an average of 13% (F = 22.4; p,0.001), compared to their state before the injection, and no significant changes were recorded over the subsequent 45 minutes (F = 0.1; p = 0.74, Fig. 2)
This slight, though consistent, stomatal closure reflected a response to the physical handing of the plants, and served as a baseline for the comparison of plant responses to the stress treatment

Summary

Introduction

Signal perception, learning and decision-making abilities are usually thought to rely on sophisticated central nervous systems (CNS); information acquisition and communication are ubiquitous even among the oldest and most rudimentary life forms [1,2,3,4]. Recent evidence demonstrates that plants are able to communicate with both allies and foes [6,7,9,10,11,12]. Following local stress or damage, plants increase local resistance and defense, and induce defensive responses in remote organs of the same plant [13,14,15]. Some plants release volatile organic compounds (VOC) that attract natural enemies of their herbivores [reviewed in 10], induce chemical defenses in their undamaged neighbours [e.g. 16], and prime them to respond more readily and intensely to subsequent herbivore attacks [12,17,18]. Belowground signaling has been demonstrated to both affect plant interactions with diverse soil micro- and macro-organisms [19] and to intricately mediate competitive interactions between plants [11,20,21]

Methods

Results

Conclusion