The water to solute permeability ratio governs the osmotic volume dynamics in beetroot vacuoles

Autores
Vitali, Victoria; Sutka, Moira; Amodeo, Gabriela; Chara, Osvaldo; Ozu, Marcelo
Año de publicación
2016
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
Plant cell vacuoles occupy up to 90% of the cell volume and, beyond their physiological function, are constantly subjected to water and solute exchange. The osmotic flow and vacuole volume dynamics relies on the vacuole membrane -the tonoplast- and its capacity to regulate its permeability to both water and solutes. The osmotic permeability coefficient (Pf) is the parameter that better characterizes the water transport when submitted to an osmotic gradient. Usually, Pf determinations are made in vitro from the initial rate of volume change, when a fast (almost instantaneous) osmolality change occurs. When aquaporins are present, it is accepted that initial volume changes are only due to water movements. However, in living cells osmotic changes are not necessarily abrupt but gradually imposed. Under these conditions, water flux might not be the only relevant driving force shaping the vacuole volume response. In this study, we quantitatively investigated volume dynamics of isolated Beta vulgaris root vacuoles under progressively applied osmotic gradients at different pH, a condition that modifies the tonoplast Pf. We followed the vacuole volume changes while simultaneously determining the external osmolality time-courses and analyzing these data with mathematical modeling. Our findings indicate that vacuole volume changes, under progressively applied osmotic gradients, would not depend on the membrane elastic properties, nor on the non-osmotic volume of the vacuole, but on water and solute fluxes across the tonoplast. We found that the volume of the vacuole at the steady state is determined by the ratio of water to solute permeabilites (Pf /Ps), which in turn is ruled by pH. The dependence of the permeability ratio on pH can be interpreted in terms of the degree of aquaporin inhibition and the consequently solute transport modulation. This is relevant in many plant organs such as root, leaves, cotyledons, or stems that perform extensive rhythmic growth movements, which very likely involve considerable cell volume changes within seconds to hours.
Instituto de Física de Líquidos y Sistemas Biológicos
Facultad de Ciencias Exactas
Materia
Ciencias Exactas
Beta vulgaris
Gradual gradients
Mathematical modeling
Red beet
Simulation
Solute flux
Vacuole
Water flux
Nivel de accesibilidad
acceso abierto
Condiciones de uso
http://creativecommons.org/licenses/by/4.0/
Repositorio
SEDICI (UNLP)
Institución
Universidad Nacional de La Plata
OAI Identificador
oai:sedici.unlp.edu.ar:10915/85928
Acceder
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oai_identifier_str oai:sedici.unlp.edu.ar:10915/85928
network_acronym_str SEDICI
repository_id_str 1329
network_name_str SEDICI (UNLP)
spelling The water to solute permeability ratio governs the osmotic volume dynamics in beetroot vacuolesVitali, VictoriaSutka, MoiraAmodeo, GabrielaChara, OsvaldoOzu, MarceloCiencias ExactasBeta vulgarisGradual gradientsMathematical modelingRed beetSimulationSolute fluxVacuoleWater fluxPlant cell vacuoles occupy up to 90% of the cell volume and, beyond their physiological function, are constantly subjected to water and solute exchange. The osmotic flow and vacuole volume dynamics relies on the vacuole membrane -the tonoplast- and its capacity to regulate its permeability to both water and solutes. The osmotic permeability coefficient (P<SUB>f</SUB>) is the parameter that better characterizes the water transport when submitted to an osmotic gradient. Usually, P<SUB>f</SUB> determinations are made <i>in vitro</i> from the initial rate of volume change, when a fast (almost instantaneous) osmolality change occurs. When aquaporins are present, it is accepted that initial volume changes are only due to water movements. However, in living cells osmotic changes are not necessarily abrupt but gradually imposed. Under these conditions, water flux might not be the only relevant driving force shaping the vacuole volume response. In this study, we quantitatively investigated volume dynamics of isolated <i>Beta vulgaris</i> root vacuoles under progressively applied osmotic gradients at different pH, a condition that modifies the tonoplast P<SUB>f</SUB>. We followed the vacuole volume changes while simultaneously determining the external osmolality time-courses and analyzing these data with mathematical modeling. Our findings indicate that vacuole volume changes, under progressively applied osmotic gradients, would not depend on the membrane elastic properties, nor on the non-osmotic volume of the vacuole, but on water and solute fluxes across the tonoplast. We found that the volume of the vacuole at the steady state is determined by the ratio of water to solute permeabilites (P<SUB>f</SUB> /P<SUB>s</SUB>), which in turn is ruled by pH. The dependence of the permeability ratio on pH can be interpreted in terms of the degree of aquaporin inhibition and the consequently solute transport modulation. This is relevant in many plant organs such as root, leaves, cotyledons, or stems that perform extensive rhythmic growth movements, which very likely involve considerable cell volume changes within seconds to hours.Instituto de Física de Líquidos y Sistemas BiológicosFacultad de Ciencias Exactas2016info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionArticulohttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdfhttp://sedici.unlp.edu.ar/handle/10915/85928enginfo:eu-repo/semantics/altIdentifier/issn/1664-462Xinfo:eu-repo/semantics/altIdentifier/doi/10.3389/fpls.2016.01388info:eu-repo/semantics/openAccesshttp://creativecommons.org/licenses/by/4.0/Creative Commons Attribution 4.0 International (CC BY 4.0)reponame:SEDICI (UNLP)instname:Universidad Nacional de La Platainstacron:UNLP2026-06-23T10:39:15Zoai:sedici.unlp.edu.ar:10915/85928Institucionalhttp://sedici.unlp.edu.ar/Universidad públicaNo correspondehttp://sedici.unlp.edu.ar/oai/snrdalira@sedici.unlp.edu.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:13292026-06-23 10:39:16.163SEDICI (UNLP) - Universidad Nacional de La Platafalse
dc.title.none.fl_str_mv The water to solute permeability ratio governs the osmotic volume dynamics in beetroot vacuoles
title The water to solute permeability ratio governs the osmotic volume dynamics in beetroot vacuoles
spellingShingle The water to solute permeability ratio governs the osmotic volume dynamics in beetroot vacuoles
Vitali, Victoria
Ciencias Exactas
Beta vulgaris
Gradual gradients
Mathematical modeling
Red beet
Simulation
Solute flux
Vacuole
Water flux
title_short The water to solute permeability ratio governs the osmotic volume dynamics in beetroot vacuoles
title_full The water to solute permeability ratio governs the osmotic volume dynamics in beetroot vacuoles
title_fullStr The water to solute permeability ratio governs the osmotic volume dynamics in beetroot vacuoles
title_full_unstemmed The water to solute permeability ratio governs the osmotic volume dynamics in beetroot vacuoles
title_sort The water to solute permeability ratio governs the osmotic volume dynamics in beetroot vacuoles
dc.creator.none.fl_str_mv Vitali, Victoria
Sutka, Moira
Amodeo, Gabriela
Chara, Osvaldo
Ozu, Marcelo
author Vitali, Victoria
author_facet Vitali, Victoria
Sutka, Moira
Amodeo, Gabriela
Chara, Osvaldo
Ozu, Marcelo
author_role author
author2 Sutka, Moira
Amodeo, Gabriela
Chara, Osvaldo
Ozu, Marcelo
author2_role author
author
author
author
dc.subject.none.fl_str_mv Ciencias Exactas
Beta vulgaris
Gradual gradients
Mathematical modeling
Red beet
Simulation
Solute flux
Vacuole
Water flux
topic Ciencias Exactas
Beta vulgaris
Gradual gradients
Mathematical modeling
Red beet
Simulation
Solute flux
Vacuole
Water flux
dc.description.none.fl_txt_mv Plant cell vacuoles occupy up to 90% of the cell volume and, beyond their physiological function, are constantly subjected to water and solute exchange. The osmotic flow and vacuole volume dynamics relies on the vacuole membrane -the tonoplast- and its capacity to regulate its permeability to both water and solutes. The osmotic permeability coefficient (P<SUB>f</SUB>) is the parameter that better characterizes the water transport when submitted to an osmotic gradient. Usually, P<SUB>f</SUB> determinations are made <i>in vitro</i> from the initial rate of volume change, when a fast (almost instantaneous) osmolality change occurs. When aquaporins are present, it is accepted that initial volume changes are only due to water movements. However, in living cells osmotic changes are not necessarily abrupt but gradually imposed. Under these conditions, water flux might not be the only relevant driving force shaping the vacuole volume response. In this study, we quantitatively investigated volume dynamics of isolated <i>Beta vulgaris</i> root vacuoles under progressively applied osmotic gradients at different pH, a condition that modifies the tonoplast P<SUB>f</SUB>. We followed the vacuole volume changes while simultaneously determining the external osmolality time-courses and analyzing these data with mathematical modeling. Our findings indicate that vacuole volume changes, under progressively applied osmotic gradients, would not depend on the membrane elastic properties, nor on the non-osmotic volume of the vacuole, but on water and solute fluxes across the tonoplast. We found that the volume of the vacuole at the steady state is determined by the ratio of water to solute permeabilites (P<SUB>f</SUB> /P<SUB>s</SUB>), which in turn is ruled by pH. The dependence of the permeability ratio on pH can be interpreted in terms of the degree of aquaporin inhibition and the consequently solute transport modulation. This is relevant in many plant organs such as root, leaves, cotyledons, or stems that perform extensive rhythmic growth movements, which very likely involve considerable cell volume changes within seconds to hours.
Instituto de Física de Líquidos y Sistemas Biológicos
Facultad de Ciencias Exactas
description Plant cell vacuoles occupy up to 90% of the cell volume and, beyond their physiological function, are constantly subjected to water and solute exchange. The osmotic flow and vacuole volume dynamics relies on the vacuole membrane -the tonoplast- and its capacity to regulate its permeability to both water and solutes. The osmotic permeability coefficient (P<SUB>f</SUB>) is the parameter that better characterizes the water transport when submitted to an osmotic gradient. Usually, P<SUB>f</SUB> determinations are made <i>in vitro</i> from the initial rate of volume change, when a fast (almost instantaneous) osmolality change occurs. When aquaporins are present, it is accepted that initial volume changes are only due to water movements. However, in living cells osmotic changes are not necessarily abrupt but gradually imposed. Under these conditions, water flux might not be the only relevant driving force shaping the vacuole volume response. In this study, we quantitatively investigated volume dynamics of isolated <i>Beta vulgaris</i> root vacuoles under progressively applied osmotic gradients at different pH, a condition that modifies the tonoplast P<SUB>f</SUB>. We followed the vacuole volume changes while simultaneously determining the external osmolality time-courses and analyzing these data with mathematical modeling. Our findings indicate that vacuole volume changes, under progressively applied osmotic gradients, would not depend on the membrane elastic properties, nor on the non-osmotic volume of the vacuole, but on water and solute fluxes across the tonoplast. We found that the volume of the vacuole at the steady state is determined by the ratio of water to solute permeabilites (P<SUB>f</SUB> /P<SUB>s</SUB>), which in turn is ruled by pH. The dependence of the permeability ratio on pH can be interpreted in terms of the degree of aquaporin inhibition and the consequently solute transport modulation. This is relevant in many plant organs such as root, leaves, cotyledons, or stems that perform extensive rhythmic growth movements, which very likely involve considerable cell volume changes within seconds to hours.
publishDate 2016
dc.date.none.fl_str_mv 2016
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
Articulo
http://purl.org/coar/resource_type/c_6501
info:ar-repo/semantics/articulo
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://sedici.unlp.edu.ar/handle/10915/85928
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dc.language.none.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv info:eu-repo/semantics/altIdentifier/issn/1664-462X
info:eu-repo/semantics/altIdentifier/doi/10.3389/fpls.2016.01388
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International (CC BY 4.0)
eu_rights_str_mv openAccess
rights_invalid_str_mv http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International (CC BY 4.0)
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collection SEDICI (UNLP)
instname_str Universidad Nacional de La Plata
instacron_str UNLP
institution UNLP
repository.name.fl_str_mv SEDICI (UNLP) - Universidad Nacional de La Plata
repository.mail.fl_str_mv alira@sedici.unlp.edu.ar
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