title: Diurnal regulation of water transport and aquaporin gene expression in maize roots: contribution of PIP2 proteins.
abstract: In maize (Zea mays) roots, xylem water transfer supported by root pressure occurs during the day and is less important at night. Diurnal modifications of osmotic pressure gradient between medium and xylem could not explain the oscillation of water flux in young maize roots during the day-night cycle. We observed a high turgor pressure of root cortical cells associated with a high flux. In maize roots, ZmPIP transcripts oscillate during the day-night cycle exhibiting some characteristics of genes regulated by a circadian mechanism. The PIP protein level profile is different from the mRNA pattern. Moreover, ZmPIP1 and ZmPIP2 protein levels are differentially regulated during the light and dark period and in response to continuous darkness suggesting different roles for both classes of PIP. Finally, our results suggest that aquaporins from ZmPIP2 subgroup may contribute to root water transfer by cellular pathway that occurs during the light and the dark period of the day-night cycle.
authors.affiliation: Institut de Biotechnologie des Plantes, CNRS-UMR 8618, Bât. 630, Université Paris-Sud, F-91405 Orsay cedex, France.
authors.forename: Félicie
authors.initials: F
authors.lastname: Lopez
authors.forename: Agnès
authors.initials: A
authors.lastname: Bousser
authors.forename: Igor
authors.initials: I
authors.lastname: Sissoëff
authors.forename: Marília
authors.initials: M
authors.lastname: Gaspar
authors.forename: Bertrand
authors.initials: B
authors.lastname: Lachaise
authors.forename: Jackson
authors.initials: J
authors.lastname: Hoarau
authors.forename: Aline
authors.initials: A
authors.lastname: Mahé
mesh_terms: D000595:Amino Acid Sequence; D020346:Aquaporins / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D001692:Biological Transport / Q000502:physiology / Q000528:radiation effects; D002940:Circadian Rhythm / Q000502:physiology* / Q000528:radiation effects; D003624:Darkness; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D008027:Light; D008969:Molecular Sequence Data; D009997:Osmotic Pressure / Q000528:radiation effects; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D018517:Plant Roots / Q000235:genetics / Q000502:physiology*; D017386:Sequence Homology, Amino Acid; D014867:Water / Q000502:physiology*; D003313:Zea mays / Q000235:genetics / Q000502:physiology*
chemical_list: D020346:Aquaporins; D010940:Plant Proteins; C110065:major intrinsic protein, plant; D014867:Water