title: Improving plant stress tolerance and yield production: is the tonoplast aquaporin SlTIP2;2 a key to isohydric to anisohydric conversion?
abstract: 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.
authors.affiliation: The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agricultural, Food & Environmental Quality Sciences, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
authors.forename: Nir
authors.initials: N
authors.lastname: Sade
authors.forename: Basia J
authors.initials: BJ
authors.lastname: Vinocur
authors.forename: Alex
authors.initials: A
authors.lastname: Diber
authors.forename: Arava
authors.initials: A
authors.lastname: Shatil
authors.forename: Gil
authors.initials: G
authors.lastname: Ronen
authors.forename: Hagit
authors.initials: H
authors.lastname: Nissan
authors.forename: Rony
authors.initials: R
authors.lastname: Wallach
authors.forename: Hagai
authors.initials: H
authors.lastname: Karchi
authors.forename: Menachem
authors.initials: M
authors.lastname: Moshelion
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects; D018533:Biomass; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D049452:Green Fluorescent Proteins / Q000378:metabolism; D018551:Solanum lycopersicum / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D009995:Osmosis / Q000187:drug effects; D010539:Permeability / Q000187:drug effects; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018526:Plant Transpiration / Q000187:drug effects / Q000502:physiology*; D030821:Plants, Genetically Modified; D021381:Protein Transport / Q000187:drug effects; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology; D013312:Stress, Physiological / Q000187:drug effects; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism; D014867:Water / Q000378:metabolism
chemical_list: D008565:Membrane Proteins; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; C077491:tonoplast intrinsic protein, plant; D014867:Water; D049452:Green Fluorescent Proteins; D012965:Sodium Chloride