New Phytologist 197 (2013), 6–8.
Since its publication, it has been brought to our attention that some information presented in the commentary by Dodd (2013) is misleading and the work of Shatil-Cohen et al. (2011) was not appropriately acknowledged. The author has amended the text to clarify this.
In the third paragraph the text should read:
In contrast to previous reports where incubation of WT leaf mesophyll protoplasts in 1 μM ABA for 1–4 h had no significant effect on osmotic water permeability (Morillon & Chrispeels, 2001; Shatil-Cohen et al., 2011), incubating bundle sheath protoplasts in 1 μM ABA for 1 h decreased osmotic water permeability by c. 40% (Shatil-Cohen et al., 2011). This demonstrates that ionic regulation of different cell types is differentially responsive to ABA (Shatil-Cohen et al., 2011), which would interact with spatial differences in ABA concentration observed in different cell types (Christmann et al., 2007) in regulating hydraulic responses to ABA.
In the fifth paragraph the text should read:
Furthermore, in some calculations of Kleaf that rely on measuring leaf water potential (Ψleaf) and transpiration rate of detached leaves, ABA feeding did not statistically change Ψleaf (Pantin et al., 2012). In this case, effects of ABA on Kleaf (hydraulic) and transpiration rate (chemical) are confounded. By contrast, supplying 10 μM ABA via the xylem to detached Arabidopsis leaves decreased Ψleaf by c. 0.05 MPa, as well as transpiration rate and Kleaf (Shatil-Cohen et al., 2011). Differences in the response of detached leaf Ψleaf to xylem-supplied ABA suggest that Kleaf should be measured using techniques that do not rely on quantifying detached leaf transpiration rate (Sack et al., 2002), in plants of contrasting ABA status (Thompson et al., 2007). This may provide direct evidence that xylem-supplied ABA does indeed act as a regulator of Kleaf.
Finally, the third sentence of the sixth paragraph should read:
An alternative view arising from previous work (Shatil-Cohen et al., 2011) is that synergistic effects of xylem-supplied ABA (in the nanomolar range) on both Kleaf and transpiration create a feedforward response eliciting stomatal closure, perhaps via transient changes in leaf water status sensitizing guard cells to existing ABA concentrations (Tardieu & Davies, 1992).
We apologize to our readers for these mistakes.