title: Differential responses of plasma membrane aquaporins in mediating water transport of cucumber seedlings under osmotic and salt stresses.
abstract: It has long been recognized that inhibition of plant water transport by either osmotic stress or salinity is mediated by aquaporins (AQPs), but the function and regulation of AQPs are highly variable among distinct isoforms and across different species. In this study, cucumber seedlings were subjected to polyethylene glycol (PEG) or NaCl stress for duration of 2 h or 24 h. The 2 h treatment with PEG or NaCl had non-significant effect on the expression of plasma membrane AQP (CsPIPs) in roots, indicating the decrease in hydraulic conductivity of roots (Lpr ) and root cells (Lprc ) measured in these conditions were due to changes in AQP activity. After both 2 h and 24 h PEG or NaCl exposure, the decrease in hydraulic conductivity of leaves (Kleaf ) and leaf cells (Lplc ) could be attributed to a down-regulation of the two most highly expressed isoforms, CsPIP1;2 and CsPIP2;4. In roots, both Lpr and Lprc were further reduced after 24 h PEG exposure, but partially recovered after 24 h NaCl treatment, which were consistent with changes in the expression of CsPIP genes. Overall, the results demonstrated differential responses of CsPIPs in mediating water transport of cucumber seedlings, and the regulatory mechanisms differed according to applied stresses, stress durations and specific organs.
authors.affiliation: Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, Guangdong, 510650, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
authors.forename: Zheng-Jiang
authors.initials: ZJ
authors.lastname: Qian
authors.forename: Juan-Juan
authors.initials: JJ
authors.lastname: Song
authors.forename: François
authors.initials: F
authors.lastname: Chaumont
authors.forename: Qing
authors.initials: Q
authors.lastname: Ye
mesh_terms: D020346:Aquaporins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D018553:Cucumis sativus / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D015536:Down-Regulation; D018506:Gene Expression Regulation, Plant; D009997:Osmotic Pressure; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D018526:Plant Transpiration / Q000502:physiology*; D054712:Salinity; D036226:Seedlings / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D012965:Sodium Chloride / Q000494:pharmacology*; D013312:Stress, Physiological; D014867:Water / Q000378:metabolism
chemical_list: D020346:Aquaporins; D010940:Plant Proteins; D014867:Water; D012965:Sodium Chloride
keywords: hydraulic conductivity; plasma membrane intrinsic protein; pressure probe; salinity