Testing for stress cuing - the experimental setup.

<p>Circles represent rooting receptacles and connector lines represent split-root plants. Plants neighbouring the externally-induced plant (IND) either shared (SHARED; T1–T5) or did not share (UNSHARED; C1–C5) their rooting volumes with their immediate neighbours. External induction was carried out by injecting either water (control) or mannitol (osmotic stress) to the red rooting receptacle. Stomatal width was destructively measured in different experimental sets immediately before (0 min), and 15 and 60 minutes after the red receptacle was injected with either water or mannitol.</p

Stomatal responses to stress and communicated stress cues.

<p>Stomatal width of induced plants (pointed at by black arrows) and their SHARED (T1–T5) and UNSHARED (C1–C5) neighbours immediately before (0 min; A), 15 (B) and 60 (C) minutes after one of the roots of the IND plant, was injected with either water (blue) or mannitol (red). Data represent means ±1 s.e.m.; N = 6. ***: p<0.001; **: p<0.01; *: p<0.05; +: 0.05</p

Testing the validity of GC-MS quantification of mannitol.

<p>Stomatal width of plants, the roots of which have been subjected to 0 (water controls) or 3.02×10⁻⁷ M mannitol, showing that even 100-fold the minimal mannitol concentration detectable by GC-MS analyses did not evoke stomatal closure in the experimental plants.</p