Table III. Summary of evidence for and against the declines in leaf water potential (Ψleaf), turgor potential (ΨP), solute potential (ΨS), or RWC or cell volume as drivers of ABA accumulation in previous studies, and whether the putative driver is supported as important for ABA accumulation in studies using externally applied pressure, as analyzed in Table II
Cell Behavior during Dehydration Potentially Driving ABA AccumulationCorrelative Evidence for a Role in Driving ABA AccumulationEvidence against a Role in Driving ABA AccumulationSupported by Observed Effect of External Pressure on ABA Accumulation?
1. Leaf water potential declineCorrelation with ABA production in dehydrating leavesaWeak relation with ABA production in dehydrating leavesaNo: Ψleaf is 0 for the treated leaves
2. Turgor pressure declineCorrelation with ABA production in dehydrating leavesaNo: ΨP increased in the treatmentb,c; this itself should not cause ABA accumulationc
3. Solute potential declineWeak relation with ABA production in dehydrating leavesaPotentially: ΨS declined in the treatmentb
No relation to ABA production in leaf samples floated on solute solutionsd
4. Relative water content or cell volume declineCorrelation with ABA production in dehydrating leavesaYes: Increase of ABA coincided with RWC decline in four studiesb,c
  • a Pierce and Raschke (1980) and references therein.

  • b Our analysis of data of McAdam and Brodribb (2016); Sussmilch et al. (2017; Table I).

  • c Ackerson and Radin (1983); Jia et al. (2001).

  • d Creelman and Zeevaart (1985); Jia et al. (2001).