title: The effect of root cooling on hormone content, leaf conductance and root hydraulic conductivity of durum wheat seedlings (Triticum durum L.).
abstract: Root cooling of 7-day-old wheat seedlings decreased root hydraulic conductivity causing a gradual loss of relative water content during 45 min (RWC). Subsequently (in 60 min), RWC became partially restored due to a decrease in transpiration linked to lower stomatal conductivity. The decrease in stomatal conductivity cannot be attributed to ABA-induced stomatal closure, since no increase in ABA content in the leaves or in the concentration in xylem sap or delivery of ABA from roots was found. However, decreased stomatal conductance was associated with a sharp decline in the content of cytokinins in shoots that was registered shortly after the start of root cooling and linked to increases in the activity of cytokinin-oxidase. This decrease in shoot cytokinin content may have been responsible for closing stomata, since this hormone is known to maintain stomatal opening when applied to plants. In support of this, pre-treatment with synthetic cytokinin benzyladenine was found to increase transpiration of wheat seedlings with cooled roots and bring about visible loss of turgor and wilting.
authors.affiliation: Institute of Biology of Russian Academy of Sciences, Ufa Research Center, Ufa 450054, Russia.
authors.forename: Svetlana V
authors.initials: SV
authors.lastname: Veselova
authors.forename: Rashit G
authors.initials: RG
authors.lastname: Farhutdinov
authors.forename: Stanislav Yu
authors.initials: SY
authors.lastname: Veselov
authors.forename: Guzel R
authors.initials: GR
authors.lastname: Kudoyarova
authors.forename: Dmitry S
authors.initials: DS
authors.lastname: Veselov
authors.forename: Wolfram
authors.initials: W
authors.lastname: Hartung
mesh_terms: D000040:Abscisic Acid / Q000502:physiology; D003080:Cold Temperature; D003583:Cytokinins / Q000502:physiology; D007210:Indoleacetic Acids / Q000378:metabolism; D010937:Plant Growth Regulators / Q000378:metabolism / Q000502:physiology*; D018515:Plant Leaves / Q000502:physiology*; D018517:Plant Roots / Q000502:physiology*; D018526:Plant Transpiration / Q000502:physiology; D036226:Seedlings / Q000502:physiology*; D013997:Time Factors; D014908:Triticum / Q000502:physiology*; D014867:Water / Q000378:metabolism*
chemical_list: D003583:Cytokinins; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D014867:Water; C030737:indoleacetic acid; D000040:Abscisic Acid