A New Pressure Probe Method to Determine the Average Volumetric Elastic Modulus of Cells in Plant Tissue

Murphy, Ricardo; Ortega, Joseph K. E.

doi:10.1104/pp.107.3.995

Cited by 36 publications

(30 citation statements)

References 31 publications

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“…This fact supports the claim that *V is technically equivalent to *R as a water stress index. The volumetric elastic module is a parameter that has been functionally defined using slightly different formulas (Figure 4) and using the Murphy & Ortega (1995) approach, which causes changes in this parameter only by transpirationinduced water loss. Presumably, this procedure causes smaller cellular deformations than those methods that study leaf volumetric elastic modules by introducing fluids inside plant cells with the aid of capillary pressure probes (Hüsken et al, 1978).…”

Section: Resultsmentioning

confidence: 99%

“…The appealing force of equation 4 resides in its simple dependence on the organ volume (v), which is the variable that governs the intracellular pressure (equation 5) (Husken et al, 1978, Murphy & Ortega, 1995e 1996.…”

Section: *R = (M -M S )/(M I -M W -M S )mentioning

confidence: 99%

“…For organs with thin walled cells and with small intercellular air volumes, that fine conceptual difference could be disregarded while obtaining meaningful information about the plant water deficit with aid of equations 4 and 5. There are also other approximated assumptions that have been used to apply equation 5; for instance, the assumption that the organ volume changes in proportion to its water content (Murphy & Ortega, 1995). As with any approximation, it involves errors, and an important one comes from implicitly assuming that the density of an organ does not change as it loses water; however, water density is different from the density of cell components, such as the cell wall, or the intercellular air volumes.…”

Section: *R = (M -M S )/(M I -M W -M S )mentioning

confidence: 99%

“…acephala), and chicory (Chichorium endivia L.) subjected to air dehydration. This field succedaneum of the pressure probe might be a valuable instrument considering that cell turgor pressure and cell volume are functionally related by elastic volumetric modules (Murphy & Ortega, 1995). Here, adaptations for rapid evaluation of relative water content, volumetric hydration and turgor pressure with a Wiltmeter ® instrument were studied using kale (Brassica oleracea var.…”

Section: *R = (M -M S )/(M I -M W -M S )mentioning

confidence: 99%

“…leaf volumetric elastic modules: Strictly speaking, equation 5 would only be valid for ideal organs whose cells had thin cell walls or if only the organ symplasmic volume is considered (Husken et al, 1978;Murphy & Ortega, 1995 …”

Section: Intercellular Air Volumementioning

confidence: 99%

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Evaluation of hydration indexes in kale leaves

Calbo¹,

Ferreira²

2011

Braz. J. Plant Physiol.

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Hydration indexes are practical variables for quantifying plant water stress and can be useful for agronomic purposes. Three adapted hydration indexes based on relative water content, volumetric hydration, and leaf turgor pressure were evaluated in kale (Brassica oleracea var. acephala) leaf segments. Relative water content and volumetric hydration were measured in leaf segments after a water infiltration procedure with the aim of filling its large intercellular volumes (@18%v/v). The infiltration was done using a hydrostatic weighing procedure and with the aid of vacuum to fully hydrate the leaf segments. These two relative indexes were proportional to the transpiration-induced leaf water loss. The third index, turgor pressure, was measured with a Wiltmeter ® instrument. Similarly, the turgor pressure was proportional to the leaf water loss, and it decreased from @310kPa in recently harvested leaves to zero in dehydrated leaves, after a total water loss of @23%. Turgor pressure was correlated with the other two hydration indexes using approximations of leaf volumetric elastic modules. Similar estimates were obtained because the decline between turgor pressure and the natural logarithm of these relative leaf hydration indexes was numerically similar (@900kPa). However, the volumetric hydration index seemed to be more suitable as a model, not only for being more concise but also because it showed a clearer biomechanical representation of the leaf water deficit effects.

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Section: Resultsmentioning

confidence: 99%

Section: *R = (M -M S )/(M I -M W -M S )mentioning

confidence: 99%

Section: *R = (M -M S )/(M I -M W -M S )mentioning

confidence: 99%

Section: *R = (M -M S )/(M I -M W -M S )mentioning

confidence: 99%

Section: Intercellular Air Volumementioning

confidence: 99%

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Evaluation of hydration indexes in kale leaves

Calbo¹,

Ferreira²

2011

Braz. J. Plant Physiol.

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Dimensionless numbers to study cell wall deformation of stiff mutants of Phycomyces blakesleeanus

Munoz

Ortega

2019

Plant Direct

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The sporangiophores of Phycomyces blakesleeanus are large cylindrical aerial cells that elongate vertically at rates between 10 μm/min and 60 μm/min. Wild‐type sporangiophores grow toward light, opposed to gravitational acceleration and away from solid barriers (tropic responses). Sporangiophores of stiff mutants C149 and C216 exhibit diminished tropic (bending) responses. Originally, it was thought that the altered genes affect the “stiffness” (elastic wall deformation) of the cell wall. Subsequent investigations employing the pressure probe demonstrated that the irreversible (plastic) wall deformation was smaller for the stiff mutants compared to wild type and could account for the diminished tropic responses. However, it was not shown whether the elastic wall deformation was altered in these stiff mutants. Recent theoretical studies have identified dimensionless numbers that can be used to quantitate the magnitudes of biophysical processes involved in expansive growth of walled cells. In this study, dimensionless numbers are used to determine the magnitudes of elastic deformation rate, plastic deformation rate, and stress relaxation rate of the cell wall during expansive growth of the stiff mutant sporangiophores. It is found that the altered genes reduce stress relaxation rates and plastic deformation rates of the wall, but do not significantly alter the magnitude of the elastic deformation rates of the wall. These results indicate that the mutant genes reduce wall loosening chemistry in these sporangiophores and the genetic mutation is not expressed in a change in “wall stiffness,” but in “wall viscosity” or “wall extensibility.”

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Non-invasive assessment of the physiological role of leaf aerenchyma in Hippeastrum Herb. and its relation to plant water status

Cabrita

2022

Planta

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Main conclusion The leaf patch clamp pressure probe combined with gas exchange measurements provides a non-invasive approach for measuring leaf aerenchyma pressure and study its physiological role in plants. Abstract The non-invasive leaf patch clamp pressure probe (LPCP) measures the output pressure, Pp, in response to the pressure applied by two magnets clamped to a leaf. In many plant species, it has been observed that the diel pattern of Pp follows the changes in the leaf turgor pressure reversely. The genus Hippeastrum comprises 143 species and many hybrids and cultivars of high economic value within Amaryllidaceae. Their leaves are characterized by the presence of aerenchyma composed of lacunae, running throughout the leaf and composing most of the mesophyll volume. In Hippeastrum, the diel changes of the LPCP output pressure are the reverse of that observed on the air pressure in the leaf aerenchyma, Pa, which depends on the changes in the leaf vapor pressure occurring during photosynthesis. A theoretical model is proposed and confirmed experimentally by LPCP and gas exchange measurements. The output pressure, Pp, in Hippeastrum can be related to the plant water status through the gas exchange processes that occur during photosynthesis. Considering the natural habitats of Hippeastrum species, these results agree with the physiological role of leaf aerenchyma in facilitating gas transport and light scattering in leaves, thus contributing to the photosynthetic efficiency of these plants under adverse environments. A second, but supplemental, interpretation of the LPCP output pressure, Pp, when applied on species in which the aerenchyma constitutes most of the mesophyll volume is presented.

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A New Pressure Probe Method to Determine the Average Volumetric Elastic Modulus of Cells in Plant Tissue

Cited by 36 publications

References 31 publications

Evaluation of hydration indexes in kale leaves

Evaluation of hydration indexes in kale leaves

Dimensionless numbers to study cell wall deformation of stiff mutants of Phycomyces blakesleeanus

Non-invasive assessment of the physiological role of leaf aerenchyma in Hippeastrum Herb. and its relation to plant water status

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