<i>In Situ</i> Measurement of Epidermal Cell Turgor, Leaf Water Potential, and Gas Exchange in <i>Tradescantia virginiana</i> L.

Shackel, Kenneth A.; Brinckmann, Enno

doi:10.1104/pp.78.1.66

Cited by 103 publications

(54 citation statements)

References 10 publications

(14 reference statements)

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“…another or flow largely through the bundle sheath extensions in species that possess them (Armacost, 1944;Wylie, 1946;McClendon, 1992) to the epidermis. Finally, evaporation might occur only near the stomata (Wylie, 1943(Wylie, , 1946Tyree and Yianoulis, 1980;Shackel and Brinckmann, 1985) or, alternatively, take place throughout the spongy mesophyll (Davies, 1986;Nonami and Schulze, 1989;Nonami et al, 1991). There is a close agreement between measurements of R leaf using methods that flood the air spaces of the leaf mesophyll once water leaves the xylem and bundle sheath (e.g.…”

Section: Partitioning Of Leaf Hydraulic Resistance: Water Flow Througmentioning

confidence: 80%

Hydraulic Analysis of Water Flow through Leaves of Sugar Maple and Red Oak

2004

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Leaves constitute a substantial fraction of the total resistance to water flow through plants. A key question is how hydraulic resistance within the leaf is distributed among petiole, major veins, minor veins, and the pathways downstream of the veins. We partitioned the leaf hydraulic resistance (R leaf ) for sugar maple (Acer saccharum) and red oak (Quercus rubra) by measuring the resistance to water flow through leaves before and after cutting specific vein orders. Simulations using an electronic circuit analog with resistors arranged in a hierarchical reticulate network justified the partitioning of total R leaf into component additive resistances. On average 64% and 74% of the R leaf was situated within the leaf xylem for sugar maple and red oak, respectively. Substantial resistance-32% and 49%-was in the minor venation, 18% and 21% in the major venation, and 14% and 4% in the petiole. The large number of parallel paths (i.e. a large transfer surface) for water leaving the minor veins through the bundle sheath and out of the leaf resulted in the pathways outside the venation comprising only 36% and 26% of R leaf . Changing leaf temperature during measurement of R leaf for intact leaves resulted in a temperature response beyond that expected from changes in viscosity. The extra response was not found for leaves with veins cut, indicating that water crosses cell membranes after it leaves the xylem. The large proportion of resistance in the venation can explain why stomata respond to leaf xylem damage and cavitation. The hydraulic importance of the leaf vein system suggests that the diversity of vein system architectures observed in angiosperms may reflect variation in whole-leaf hydraulic capacity.Water flow through the leaf is one of the most important but least understood components of the whole-plant hydraulic system. The leaf hydraulic resistance (R leaf ) constitutes a significant hydraulic bottleneck, correlates with leaf structure, and apparently constrains gas exchange (Tyree and Zimmermann, 2002;Sack et al., 2003b;Sack and Tyree, 2004). R leaf is an aggregate measure; once past the petiole, water flows through a reticulate network of veins, across the bundle sheath cells, and through or around mesophyll cells before evaporation and diffusion from the stomata (Esau, 1965). Recent work has focused primarily on measurement of R leaf and its functional correlates. Few studies have attempted to determine quantitatively how the various components of the water flow pathway through the leaf contribute to its total resistance.Partitioning of R leaf is a crucial step for understanding leaf hydraulic design. Cavitation in the leaf vein xylem can substantially increase R leaf , as can physical damage to major veins; both drive reductions of leaf water potential and gas exchange Nardini et al., 2001Cochard et al., 2002;Huve et al., 2002;Sack et al., 2003a). These observations suggest that a large proportion of R leaf is situated in the veins. However, a number of studies have reported that most of the leaf resista...

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Section: Partitioning Of Leaf Hydraulic Resistance: Water Flow Througmentioning

confidence: 80%

Hydraulic Analysis of Water Flow through Leaves of Sugar Maple and Red Oak

2004

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“…The cell pressure probe is an excellent tool to acquire data on parameters such as cell turgor, cell wall elasticity, and membrane permeability and has been optimized for a number of cell types over the last decades (Steudle and Zimmermann, 1977;Hüsken et al, 1978;Cosgrove 1981Cosgrove , 1985Cosgrove , 1993Shackel and Brinckmann, 1985;Cosgrove et al, 1987;Oparka et al, 1991;Ye and Steudle, 2006;Wada et al, 2014). Unfortunately, some cell types show rapid injury responses, which make it difficult or impossible to apply this method.…”

Section: Resultsmentioning

confidence: 99%

Pico Gauges for Minimally Invasive Intracellular Hydrostatic Pressure Measurements

et al. 2014

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Intracellular pressure has a multitude of functions in cells surrounded by a cell wall or similar matrix in all kingdoms of life. The functions include cell growth, nastic movements, and penetration of tissue by parasites. The precise measurement of intracellular pressure in the majority of cells, however, remains difficult or impossible due to their small size and/or sensitivity to manipulation. Here, we report on a method that allows precise measurements in basically any cell type over all ranges of pressure. It is based on the compression of nanoliter and picoliter volumes of oil entrapped in the tip of microcapillaries, which we call pico gauges. The production of pico gauges can be accomplished with standard laboratory equipment, and measurements are comparably easy to conduct. Example pressure measurements are performed on cells that are difficult or impossible to measure with other methods.

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“…7 and 28). The increase in the maximum excursion of stomatal conductance with increasing VPD that was observed at 30°C (and occasionally at high VPD at lower temperatures) and the acceleration of opening kinetics with increasing VPD (2)(3)(4) are more likely to reflect hydropassive effects of temperature and VPD on epidermal water relations (6,10,21,25). Accelerated opening kinetics could result from reduced epidermal backpressure on the stomatal complex.…”

Section: Discussionmentioning

confidence: 99%

“…Accelerated opening kinetics could result from reduced epidermal backpressure on the stomatal complex. Reduced epidermal turgor could arise from enhanced cuticular conductance at high temperature (22,23) and from the increased driving force for peristomatal or cuticular transpiration at high VPD (17) as well as from enhanced stomatal transpiration in the absence of feedforward responses (18,25). Accelerated opening kinetics would increase the maximum excursion of stomatal opening, unless time to initiation of stomatal closure were decreased in a compensatory manner.…”

Section: Discussionmentioning

confidence: 99%

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The Magnitude of the Stomatal Response to Blue Light

Assmann

Grantz²

1990

Plant Physiol.

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The effect of leaf-air vapor pressure difference (VPD) on the magnitude of the stomatal response to blue light was investigated in soybean (Glycine max) by administering blue light pulses (22 seconds by 120 micromoles per square meter per second) at different levels of VPD and temperature. At 20 OC and 25 OC, the magnitude of the integrated conductance response decreased with increasing VPD (0.4 to 2.6 kiloPascals), due to an earlier onset of stomatal closure that terminated the pulse response. In contrast, at 30 OC this magnitude increased with rising VPD (0.9 to 3.5 kiloPascals), due to an increasing maximum excursion of the conductance response despite the accelerated onset of stomatal closure. When the feedforward response of stomata to humidity caused steady state transpiration to decrease with increasing VPD, the magnitude of the pulse-induced conductance response correlated with VPD rather than with transpiration. This suggests that water relations or metabolite movements within epidermal rather than bulk leaf tissue interacted with guard cell photobiological properties in regulating the magnitude of the blue light response. VPD Experimental ProtocolThe leaf was placed in the cuvette and allowed to reach steady-state levels of assimilation and stomatal conductance at a low VPD (ca. 0.4 kPa at 20°C, 0.9 kPA at 30 C). A preliminary blue pulse was administered so that all test pulses, including the first, would be preceded by blue light stimulation. Steady-state was defined as near stability over ten minutes and was quantified as the average over that time of conductance, assimilation, transpiration, VPD, and RH. Blue light pulses were then administered and gas exchange parameters monitored without adjusting any system controls until conductance regained a steady state value. The magnitude of the blue light response (Fig. 1) was quantified as the integrated conductance above the baseline following stimulation by blue light (11,27). Under conditions of slowly changing baseline conductance (increasing or decreasing) the drifting baseline was incorporated into estimates of pulse magnitude as shown diagramatically in Figure 1. The components that determined this magnitude, including duration of response, maximum excursion of stomatal conductance above baseline, and time to reversal from stomatal opening to stomatal closure (T7&v) were also determined (Fig. 1). Kinetic parameters associated with rates of conductance increase and recovery were determined from the slopes of tangents to the ascending and descending portions of the pulse response curves as described previously (2). The water cost of a response to blue light was defined as the integrated transpiration above the baseline after a blue light pulse. Several replicate experiments were performed at each of 20 C, 25 C, and 30 'C. Figures depict data from representative leaves, while tables contain statistical evaluations of the pooled data. RESULTSThe Blue Light Response A transient increase in stomatal conductance was observed following a brief p...

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In Situ Measurement of Epidermal Cell Turgor, Leaf Water Potential, and Gas Exchange in Tradescantia virginiana L.

Cited by 103 publications

References 10 publications

Hydraulic Analysis of Water Flow through Leaves of Sugar Maple and Red Oak

Hydraulic Analysis of Water Flow through Leaves of Sugar Maple and Red Oak

Pico Gauges for Minimally Invasive Intracellular Hydrostatic Pressure Measurements

The Magnitude of the Stomatal Response to Blue Light

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