Abscisic Acid Accumulation in Cotton Leaves in Response to Dehydration at High Pressure

Abstract

Pressure-volume techniques were utilized to examine the control of abscisic acid (ABA) accumulation in dehydrated cotton (Gossypium hirsutum L. cv Tamcot SP 37) leaves. Leaves were rapidly dehydrated in a pressure chamber to a balance pressure coincident with the loss of cellular turgor, and then the pressure was either maintained at that level or released. Rapid accumulation of ABA began within two hours after the balance pressure was achieved, whether or not the high pressure potential of the cells was maintained by the externally imposed pressure. The results show that loss of pressure per se does not trigger ABA accumulation in dehydrated leaves. Rather, the stimulus may be related to cellular shrinkage and relaxation of the elastic wall.

The natural and social history of the indigenous lands and protected areas corridor of the Xingu River basin

“…corresponding to a decline in RWC or volume, independently of C P . An important control showed that pressurizing leaves entirely enclosed within the pressure chamber-without the petiole protruding and thus without leaf water lossonly led to minimal stimulation of ABA accumulation, indicating that increases in C P alone were not the stimulus (Ackerson and Radin, 1983). This same approach was revived in recent articles Sussmilch et al, 2017), though these authors argued that the application of external pressure would reduce leaf turgor and that this reduction of turgor triggered ABA accumulation.…”

“…When cotton (Gossypium hirsutum) or maize leaves were dehydrated under sustained pressure in a pressure chamber, such that the leaves lost water by extrusion through the petiole, ABA accumulated (Ackerson and Radin, 1983;Jia et al, 2001). The authors argued that pressurizing the leaves during dehydration maintained cell turgor, and thus that ABA accumulation was driven instead by cellular volume shrinkage or relaxation of the cell wall, i.e.…”

“…Our analysis also establishes that declining C leaf itself was not the driver, because it was equal across treatments and held at ≅ 0 MPa. Assuming that ABA accumulation was not driven by the increase of C P (Ackerson and Radin, 1983), nor by the reduction of C S associated with the increase in cellular solute concentrations (Creelman and Zeevaart, 1985), the decline of cell volume and its associated processes would be responsible (Table III). We note that a strong but very brief reduction of C P would have been triggered when the external pressure was released and the leaf removed from the chamber before snap freezing for ABA analysis.…”

“…Indeed, the external pressure dehydration treatment (Ackerson and Radin, 1983;Jia et al, 2001;Sussmilch et al, 2017) enables the independent resolution of C P decline from RWC decline, whereas in vivo these typically occur together. The method thus provides a powerful tool to distinguish these as drivers of physiological responses.…”

ABA Accumulation in Dehydrating Leaves Is Associated with Decline in Cell Volume, Not Turgor Pressure

“…Summary of evidence for and against the declines in leaf water potential (C leaf ), turgor potential (C P ), solute potential (C S ), 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 I). c Ackerson and Radin (1983); Jia et al (2001).…”