Aquaporin regulation in poplar and spruce trees under environmental change.

• Author / Creator

  Laur, Joan

• This dissertation describes a series of experiments that examined: 1) hydraulic responses of Populus trichocarpa x deltoides, Populus trichocarpa and Picea glauca plants to change in their surrounding environment; 2) Changes of aquaporin expression in response to such changes.
  In the first study, we demonstrated that changes of the transpirational demand is related to fine adjustment of root water uptake that is associated with up-regulation of plasma membrane intrinsic proteins isoforms (PIPs) in hybrid poplar saplings. PIP1 proteins are mostly localized in the endodermis where they may facilitate water movement to the stele. In the second study, we investigated the dynamics of leaf hydraulics in P. trichocarpa saplings exposed to a dehydration-rewatering episode. Fast leaf recovery was associated with an increase in expression of several tonoplast intrinsic proteins isoforms (TIPs) localized in xylem parenchyma. In the third study, we considered the physiological importance of foliar water uptake in P. glauca plants exposed to drought. In order to study the role of aquaporin in needle water uptake, we characterized the aquaporin family in white spruce. Our findings are consistent with the hypothesis that aquaporins facilitate radial water movement from the atmosphere towards the needle vascular tissue, therefore providing an alternate water source for embolism repair in conifers.
  These results suggest the several roles of aquaporin regulation in the dynamic and fine adjustment of tree-water relations.

• Subjects / Keywords

  • Radial water flow
  • Spruce
  • Leaf hydraulic conductance
  • Poplar
  • Transpirational demand
  • Regulation
  • Xylem refilling
  • Aquaporins
  • Root hydraulics

• Graduation date

  Fall 2014

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3ZQ2J

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.