title: Short-term control of maize cell and root water permeability through plasma membrane aquaporin isoforms.
abstract: Although it is widely accepted that aquaporins are involved in the regulation of root water uptake, the role of specific isoforms in this process is poorly understood. The mRNA expression and protein level of specific plasma membrane intrinsic proteins (PIPs) were analysed in Zea mays in relation to cell and root hydraulic conductivity. Plants were analysed during the day/night period, under different growth conditions (aeroponics/hydroponics) and in response to short-term osmotic stress applied through polyethylene glycol (PEG). Higher protein levels of ZmPIP1;2, ZmPIP2;1/2;2, ZmPIP2;5 and ZmPIP2;6 during the day coincided with a higher water permeability of root cortex cells during the day compared with night period. Similarly, plants which were grown under aeroponic conditions and which developed a hypodermis ('exodermis') with Casparian bands, effectively forcing more water along a membranous uptake path across roots, showed increased levels of ZmPIP2;5 and ZmPIP1;2 in the rhizodermis and exodermis. When PEG was added to the root medium (2-8 h), expression of PIPs and cell water permeability in roots increased. These data support a role of specific PIP isoforms, in particular ZmPIP1;2 and ZmPIP2;5, in regulating root water uptake and cortex cell hydraulic conductivity in maize.
authors.affiliation: Institut des Sciences de la Vie, Université catholique de Louvain, Croix du Sud 4-L7.07.14, B-1348 Louvain-la-Neuve, Belgium.
authors.forename: Charles
authors.initials: C
authors.lastname: Hachez
authors.forename: Dmitry
authors.initials: D
authors.lastname: Veselov
authors.forename: Qing
authors.initials: Q
authors.lastname: Ye
authors.forename: Hagen
authors.initials: H
authors.lastname: Reinhardt
authors.forename: Thorsten
authors.initials: T
authors.lastname: Knipfer
authors.forename: Wieland
authors.initials: W
authors.lastname: Fricke
authors.forename: François
authors.initials: F
authors.lastname: Chaumont
mesh_terms: D020346:Aquaporins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D002940:Circadian Rhythm; D018506:Gene Expression Regulation, Plant; D009997:Osmotic Pressure; D010539:Permeability; D010788:Photosynthesis; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000502:physiology*; D018526:Plant Transpiration; D011092:Polyethylene Glycols / Q000494:pharmacology; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics; D036226:Seedlings / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D014867:Water / Q000378:metabolism*; D003313:Zea mays / Q000235:genetics / Q000378:metabolism*
chemical_list: D020346:Aquaporins; D010940:Plant Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger; D018749:RNA, Plant; C110065:major intrinsic protein, plant; D014867:Water; D011092:Polyethylene Glycols