title: Leaf hydraulic conductance and mesophyll conductance are not closely related within a single species.
abstract: Stomata represent one resistor in a series of resistances for carbon and water exchange between the leaf and the atmosphere; the remaining resistors occurring within the leaf, commonly represented as mesophyll conductance to CO2, gm, and leaf hydraulic conductance, kLeaf. Recent studies have proposed that gmand kLeafmay be coordinated across species because of shared pathways. We assessed the correlation between gmand kLeafwithin cotton, under growth CO2partial pressure and irradiance treatments and also with short-term variation in irradiance and humidity. gmwas estimated using two isotopic techniques that allowed partitioning of total gm(Δ13C-gm) into cell wall plus plasma membrane conductance (Δ18O-gm) and chloroplast membrane conductance (gcm). A weak correlation was found between Δ13C-gmand kLeafonly when measured under growth conditions. However, Δ18O-gmwas related to kLeafunder both short-term environmental variation and growth conditions. Partitioning gmshowed that gcmwas not affected by short-term changes in irradiance or correlated with kLeaf, but was strongly reduced at high growth CO2partial pressure. Thus, simultaneous measurements of gm, kLeafand gcmsuggest independent regulation of carbon and water transport across the chloroplast membrane with limited coordinated regulation across the cell wall and plasma membrane.
authors.affiliation: Centre for Carbon, Water and Food, Faculty of Agriculture and Environment, The University of Sydney, 380 Werombi Rd, New South Wales, 2570, Australia.
authors.forename: Karen E
authors.initials: KE
authors.lastname: Loucos
authors.affiliation: Department of Biology, San Francisco State University, San Francisco, CA, 94132, USA.
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Simonin
authors.affiliation: Centre for Carbon, Water and Food, Faculty of Agriculture and Environment, The University of Sydney, 380 Werombi Rd, New South Wales, 2570, Australia.
authors.forename: Margaret M
authors.initials: MM
authors.lastname: Barbour
mesh_terms: D002245:Carbon Dioxide / Q000494:pharmacology; D002247:Carbon Isotopes; D004058:Diffusion; D003368:Gossypium / Q000033:anatomy & histology / Q000187:drug effects / Q000254:growth & development; D008027:Light; D058503:Mesophyll Cells / Q000187:drug effects / Q000502:physiology*; D009010:Monte Carlo Method; D018515:Plant Leaves / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology*; D013045:Species Specificity; D014867:Water / Q000502:physiology*
chemical_list: D002247:Carbon Isotopes; D014867:Water; D002245:Carbon Dioxide
keywords: Gossypium hirsutum; carbon transport; mesophyll conductance to CO2; stable isotopes; water transport