Improving plant stress tolerance and yield production: Is the tonoplast aquaporin SlTIP2;2 a key to isohydric to anisohydric conversion?

Nir Sade, Basia J. Vinocur, Alex Diber, Arava Shatil, Gil Ronen, Hagit Nissan, Rony Wallach, Hagai Karchi, Menachem Moshelion*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

270 Scopus citations


• Anisohydric plants are thought to be more drought tolerant than isohydric plants. However, the molecular mechanism determining whether the plant water potential during the day remains constant or not regardless of the evaporative demand (isohydric vs anisohydric plant) is not known. • Here, it was hypothesized that aquaporins take part in this molecular mechanism determining the plant isohydric threshold. Using computational mining a key tonoplast aquaporin, tonoplast intrinsic protein 2;2 (SlTIP2;2), was selected within the large multifunctional gene family of tomato (Solanum lycopersicum) aquaporins based on its induction in response to abiotic stresses. SlTIP2;2-transformed plants (TOM-SlTIP2;2) were compared with controls in physiological assays at cellular and whole-plant levels. • Constitutive expression of SlTIP2;2 increased the osmotic water permeability of the cell and whole-plant transpiration. Under drought, these plants transpired more and for longer periods than control plants, reaching a lower relative water content, a behavior characterizing anisohydric plants. In 3-yr consecutive commercial glasshouse trials, TOM-SlTIP2;2 showed significant increases in fruit yield, harvest index and plant mass relative to the control under both normal and water-stress conditions. • In conclusion, it is proposed that the regulation mechanism controlling tonoplast water permeability might have a role in determining the whole-plant ishohydric threshold, and thus its abiotic stress tolerance.

Original languageAmerican English
Pages (from-to)651-661
Number of pages11
JournalNew Phytologist
Issue number3
StatePublished - Feb 2009


  • Anisohydric
  • Aquaporin
  • Isohydric
  • Osmotic water permeability coefficient (P)
  • Stress tolerance
  • Tonoplast
  • Transpiration
  • Water permeability


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