Table II. New analyses of cell water relation parameters during external pressurization experiments that stimulated ABA accumulation (McAdam and Brodribb, 2016; Sussmilch et al., 2017)

Pressure volume curve parameters are provided (based on methods of Sack et al., 2010): osmotic potential at full turgor (ΨS,o) and at turgor loss point (ΨS,tlp), the relative water content (RWC) at turgor loss point (RWCtlp), and the apoplastic fraction (af); see Appendix and Supplemental Data S1. The external pressure threshold for ABA production and the minimum tested time necessary for the pressure treatment to induce ABA production are provided, as well as calculated values for the water relations of the leaves using the equations provided in the Appendix: total and symplastic RWC, osmotic and turgor potentials (ΨS and ΨP, respectively), and the % increase in ΨP, the decrease in ΨS, the % increase in solute concentration c (estimated given that ΨS = −RTc, where R is the ideal gas constant and T is temperature), and the declines in total and symplastic RWC relative to turgid leaves. While the four first rows are based on data from McAdam and Brodribb (2016), the last row, marked with an asterisk, is from Sussmilch et al. (2017), and the external pressure was not a threshold for ABA accumulation but chosen to exceed turgor loss point.

SpeciesΨS,oΨS,tlpRWCtlpafDuring External Pressure Treatment
External Pressure ThresholdShortest Measured Time Req'tTotal RWCSymplastic RWCΨPΨSΨP IncreaseΨS Decreasec IncreaseTotal RWC DeclineSymplastic RWC Decline
Arabidopsis thaliana−0.684−0.80787.719.40.5200.9230.9050.76−0.7610.5−0.07210.57.669.51
Pisum sativum−0.927−1.2980.229.61600.8430.7771.19−1.1928.7−0.26628.715.722.3
Nothofagus cunninghamii−0.955−1.2496.082.81200.9670.8101.18−1.1823.4−0.22323.43.2518.9
Olea oleaster−1.91−2.3491.653.61.5600.9450.8822.17−2.1713.4−0.25613.45.4811.8
Arabidopsis thaliana*−0.684−0.80787.719.41.5*50.5620.4561.50−1.50119−0.81611943.854.4