Tree Physiology Advance Access originally published online on October 6, 2009
Tree Physiology 2009 29(11):1467-1477; doi:10.1093/treephys/tpp060
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Functional analysis of putative genes encoding the PIP2 water channel subfamily in Populus trichocarpa
1 Arnold Arboretum of Harvard University, Cambridge, USA
2 Corresponding author (fsecchi{at}oeb.harvard.edu)
3 Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, USA
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Abstract |
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We located fully sequenced putative genes of the plasma membrane intrinsic proteins (PIPs) family in the Populus trichocarpa (Torr. Gray), genome. Of 23 gene candidates, we assigned eight genes to the PIP2 subfamily. All eight putative genes were expressed in vegetative tissues (roots, leaves, bark and wood), and all of them showed water channel activity after being expressed in Xenopus oocytes. Six of eight proteins were affected by mercury ions. No proteins were affected by the presence of nickel or tungsten ions, or by lowering the pH of bathing external solution from 7.4 to 6.5. The presence of copper ions caused seven of eight PIP2 proteins to increase their water transport capacity by as much as 50%. This systematic study of the PIP2 subfamily of proteins in P. trichocarpa provides a basic overview of their activity as water channels and will be a useful reference for future physiological studies of plant water relations that use P. trichocarpa as a model system.
Keywords: aquaporin, heavy metal inhibition, water channel activity, Xenopus laevis oocytes
Received February 20, 2009; Accepted July 8, 2009