Abstract
The salt stress is one of the representative abiotic stresses that decreases growth and productivity of crops plants. The root water permeability of three barley (Hordeum Vulgare) cultivars that show a difference in the salt sensitivity was measured under salinity stress using a pressure chamber. Water permeability of salt sensitive variety did not show any difference in response to salt stress, in contrast to significant reductions of water permeability found in more salt tolerant varieties. Root water permeability of tolerant cultivars exposed to 100 mM NaCl was found to be extremely down-regulated after 1hr. Interestingly, however, water permeability was partially recovered after 4 hrs, which was followed by a re-down-regulation afterwards. Further measurements using various inhibitors indicated that at least protein phosphorylation plays an essential role in the regulation mechanism. Effects of putative phoshorylation sites on the water transport activity of HvPIP aquaporins are in progress using Xenopus laevis ooctyes.
