Pressure and Solute Potentials in Stomatal Cells of<i>Tradescantia virginiana</i>

Meidner, Hans; Bannister, P.

doi:10.1093/jxb/30.2.255

Cited by 36 publications

(38 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although 9 is teehnically difficult to measure, it has been estimated for Tradescantia virginiana to be between 1 -6 and 2-0 (Meidner & Edwards 1975;Meidner & Bannister 1979). These data are consistent with a theoretical analysis (Cooke et al 1976) that suggested a value of about 1 -5.…”

Section: Discussionsupporting

confidence: 76%

A spatially explicit model of patchy stomatal responses to humidity

Haefner

Buckley

Mott

1997

Plant Cell & Environment

View full text Add to dashboard Cite

Stomata of leaves can exhibit either temporally stable, spatially homogeneous behaviour or complex spatial and temporal dynamics, depending on environmental and physiological conditions. To test the ability of accepted physiological mechanisms to describe these patterns, we developed a simple, spatially explicit model of stomatal responses to humidity that incorporated hydraulic interactions among stomata. Model results showed qualitative agreement with experimental evidence for a number of phenomena: (1) at high humidities, whole-leaf steady-state conductance is a monotonic function of humidity; (2) the initial stomatal response following a perturbation in humidity is in the direction opposite to the final response, and (3) spatial dynamics include patch formation and selforganization similar to that observed in actual leaves. These comparisons do not eliminate other explanations, but do suggest that novel mechanisms need not be invoked to explain the diversity of spatial and temporal patterns of stomatal behaviour in leaves.

show abstract

Section: Discussionsupporting

confidence: 76%

A spatially explicit model of patchy stomatal responses to humidity

Haefner

Buckley

Mott

1997

Plant Cell & Environment

View full text Add to dashboard Cite

show abstract

“…In previous studies (7) using the same plant material, however, these psychrometers exhibited a much wider range of measured leaf water potentials, and even for the most resistive samples an equilibration time of the order of minutes for water vapor exchange between the leaf surface and the psychrometer. Although the estimate of within leaf hydraulic conductivity presented in this study (3)(4)(5) (8) and the epidermis to guard cell complex level (3,4). In general, these hypothesis suggest that stomata are situated at or near the end of the gradient and will experience greater changes in water potential for a given change in evaporative demand than the bulk leaf.…”

Section: Discussionmentioning

confidence: 66%

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

Shackel¹,

Brinckmann²

1985

Plant Physiol.

103

View full text Add to dashboard Cite

A combined system has been developed in which epidermal cell turgor, leaf water potential, and gas exchange were determined for transpiring leaves of Tradescantia virginiana L. Uniform and stable values of turgor were observed in epidermal cells (stomatal complex cells were not studied) under stable environmental conditions for both upper and lower epidermises. The changes in epidermal cell turgor that were associated with changes in leaf transpiration were larger than the changes in leaf water potential, indicating the presence of transpirationally induced within-leaf water potential gradients. Estimates of 3 to 5 millimoles per square meter per second per megapascal were obtained for the value of within-leaf hydraulic conductivity.Step changes in atmospheric humidity caused rapid changes in epidermal cell turgor with little or no initial change in stomatal conductance, indicating little direct relation between stomatal humidity response and epidermal water status. The significance of within-leaf water potential gradients to measurements of plant water potential and to current hypotheses regarding stomatal response to humidity is discussed.Since its development by Husken et al. (2), the miniaturized pressure probe has for the most part been used to estimate the water relations parameters (hydraulic conductivity and volumetric elastic modulus) of individual plant cells (e.g. 1 1). However, the value of cellular turgor itself is also considered to be a fundamentally important physiological parameter in plants (e.g. 9), particularly for current hypotheses regarding stomatal sensitivity to atmospheric humidity (e.g. as reviewed by MaierMaercker [3]). These hypotheses ascribe a central role to withinleaf water potential gradients and the consequences of these gradients to epidermal and stomatal cell turgor. In situ measurement of epidermal cell turgor is possible on attached leaves of Tradescantia virginiana L. (11), and in principle may be combined with in situ measurements of leaf gas exchange and water potential under contrasting levels of leaf transpiration. This measurement should then provide direct evidence for the occurrence of transpirationally induced within-leaf water potential gradients (10) if the differences in leaf epidermal cell turgor that are associated with differences in transpiration are larger than the corresponding changes in leaf water potential. In addition it should provide information regarding the proposed relationship between epidermal cell turgor and level of stomatal conductance (e.g.8). The following paper reports the development of a combined system for measuring epidermal cell turgor and leaf water relations parameters under controlled environmental conditions. ' Supported by the Deutsche Forschungsgemeinschaft (Sonderforschungsbereich 137).Results are also presented concerning within-leaf water potential gradients and relations between epidermal cell turgor and stomatal responses. MATERIALS AND METHODS

show abstract

“…The simple quantitative relationship between guard cell turgor (P g ), epidermal (or subsidiary) cell turgor (P e ), and stomatal aperture (a), which defines the operational potential of all stomata, is known for only a few species, and most of these have structurally similar stomata (Meidner and Bannister, 1979;Franks et al, 1998. No such data are available for the distinctive ''dumb-bell''-shaped stomata of grasses, for example, or for the more mechanically isolated stomata that are common in many pteridophytes.…”

mentioning

confidence: 99%

The Mechanical Diversity of Stomata and Its Significance in Gas-Exchange Control

2006

View full text Add to dashboard Cite

Given that stomatal movement is ultimately a mechanical process and that stomata are morphologically and mechanically diverse, we explored the influence of stomatal mechanical diversity on leaf gas exchange and considered some of the constraints. Mechanical measurements were conducted on the guard cells of four different species exhibiting different stomatal morphologies, including three variants on the classical ''kidney'' form and one ''dumb-bell'' type; this information, together with gas-exchange measurements, was used to model and compare their respective operational characteristics. Based on evidence from scanning electron microscope images of cryo-sectioned leaves that were sampled under full sun and high humidity and from pressure probe measurements of the stomatal aperture versus guard cell turgor relationship at maximum and zero epidermal turgor, it was concluded that maximum stomatal apertures (and maximum leaf diffusive conductance) could not be obtained in at least one of the species (the grass Triticum aestivum) without a substantial reduction in subsidiary cell osmotic (and hence turgor) pressure during stomatal opening to overcome the large mechanical advantage of subsidiary cells. A mechanism for this is proposed, with a corollary being greatly accelerated stomatal opening and closure. Gas-exchange measurements on T. aestivum revealed the capability of very rapid stomatal movements, which may be explained by the unique morphology and mechanics of its dumb-bell-shaped stomata coupled with ''see-sawing'' of osmotic and turgor pressure between guard and subsidiary cells during stomatal opening or closure. Such properties might underlie the success of grasses.Although the morphological diversity of stomata is widely documented (Haberlandt, 1884;Meidner and Mansfield, 1968;Allaway and Milthorpe, 1976;Ziegler, 1987;Willmer and Fricker, 1996), little is known of how this translates into functional diversity and what the environmental context of this might be. Throughout the 400 million year (Ma) history of vascular plants on land, long-term decline in atmospheric CO 2 concentration and shifts in prevailing moisture patterns have placed selective pressures on stomata to increase epidermal conductance to CO 2 diffusion and also to increase transpiration efficiency (CO 2 fixed per unit water transpired). This posed two separate problems, upon which the combination of mutation and time might have worked to give rise to the current diversity of stomatal form and function. The first centered on the simple geometric practicalities of fitting enough functional stomatal units per unit leaf surface area to meet the desired CO 2 flux as atmospheric CO 2 concentration changed, or to service an increase in photosynthetic capacity. The second centered on the performance characteristics of any new stomatal structure or configuration in relation to transpiration efficiency. Here, by examining the mechanical and performance characteristics of stomata in four different species, we explore the nature of these two problem...

show abstract

Pressure and Solute Potentials in Stomatal Cells ofTradescantia virginiana

Cited by 36 publications

References 0 publications

A spatially explicit model of patchy stomatal responses to humidity

A spatially explicit model of patchy stomatal responses to humidity

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

The Mechanical Diversity of Stomata and Its Significance in Gas-Exchange Control

Contact Info

Product

Resources

About