title: Overexpression of a plasma membrane aquaporin in transgenic tobacco improves plant vigor under favorable growth conditions but not under drought or salt stress.
abstract: Most of the symplastic water transport in plants occurs via aquaporins, but the extent to which aquaporins contribute to plant water status under favorable growth conditions and abiotic stress is not clear. To address this issue, we constitutively overexpressed the Arabidopsis plasma membrane aquaporin, PIP1b, in transgenic tobacco plants. Under favorable growth conditions, PIP1b overexpression significantly increased plant growth rate, transpiration rate, stomatal density, and photosynthetic efficiency. By contrast, PIP1b overexpression had no beneficial effect under salt stress, whereas during drought stress it had a negative effect, causing faster wilting. Our results suggest that symplastic water transport via plasma membrane aquaporins represents a limiting factor for plant growth and vigor under favorable conditions and that even fully irrigated plants face limited water transportation. By contrast, enhanced symplastic water transport via plasma membrane aquaporins may not have any beneficial effect under salt stress, and it has a deleterious effect during drought stress.
authors.affiliation: Department of Plant Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Refael
authors.initials: R
authors.lastname: Aharon
authors.forename: Yosepha
authors.initials: Y
authors.lastname: Shahak
authors.forename: Smadar
authors.initials: S
authors.lastname: Wininger
authors.forename: Rozalina
authors.initials: R
authors.lastname: Bendov
authors.forename: Yoram
authors.initials: Y
authors.lastname: Kapulnik
authors.forename: Gad
authors.initials: G
authors.lastname: Galili
mesh_terms: D020346:Aquaporins / Q000235:genetics* / Q000378:metabolism; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects / Q000502:physiology; D018526:Plant Transpiration / Q000187:drug effects / Q000502:physiology; D030821:Plants, Genetically Modified; D012965:Sodium Chloride / Q000494:pharmacology; D013314:Stress, Mechanical; D014026:Nicotiana / Q000235:genetics* / Q000254:growth & development; D014867:Water / Q000494:pharmacology
chemical_list: D020346:Aquaporins; D029681:Arabidopsis Proteins; D008565:Membrane Proteins; D012965:Sodium Chloride; D014867:Water; C085550:At2g45960 protein, Arabidopsis