Aquaporins and leaf hydraulics: poplar sheds new light.
To help understand leaf hydraulic conductance (Kleaf) modulation under high irradiance, well-watered poplars (Populus trichocarpa Torr. & Gray ex Hook and Populus nigra L.) were studied diurnally at molecular and ecophysiological scales. Transcriptional and translational modulations of plasma membrane intrinsic protein (PIP) aquaporins were evaluated in leaf samples during diurnal time courses. Among the 15 poplar PIP genes, a subset of two PIP1s and seven PIP2s are precociously induced within the first hour of the photoperiod concomitantly with a Kleaf increase. Since expression patterns were cyclic and reproducible over several days, we hypothesized that endogenous signals could be involved in PIP transcriptional regulation. To address this question, plants were submitted to forced darkness during their subjective photoperiod and compared with their control counterparts, which showed that some PIP1s and PIP2s have circadian regulation while others did not. Promoter analysis revealed that a large number of hormone, light, stress response and circadian elements are present. Finally, involvement of aquaporins is supported by the reduction of Kleaf by HgCl2 treatment.
Clermont Université, Université Blaise Pascal, UMR547 PIAF, BP 10448, F-63000 Clermont-Ferrand, France.
David
D
Lopez
Jean-Stéphane
JS
Venisse
Boris
B
Fumanal
François
F
Chaumont
Esther
E
Guillot
Mark J
MJ
Daniels
Hervé
H
Cochard
Jean-Louis
JL
Julien
Aurélie
A
Gousset-Dupont
D020346:Aquaporins / Q000235:genetics / Q000378:metabolism*; D002940:Circadian Rhythm / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D008027:Light; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018526:Plant Transpiration / Q000235:genetics / Q000502:physiology; D032107:Populus / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects
D020346:Aquaporins; D010940:Plant Proteins
Aquaporin; Circadian regulation; Leaf hydraulic conductance (Kleaf); Light; Poplar (Populus trichocarpa, Populus nigra); Promoter