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1983[X]
1Author    Wolfram Hartung, Barbara DierichRequires cookie*
 Title    Uptake and Release of Abscisic Acid by Runner Bean Root Tip Segments  
 Abstract    Uptake o f abscisic acid by 5 mm long decapped root tips is a linear function o f the external ABA concentration in the range o f 2.9 x 10-8 m to 10~4 m and decreases dramatically with in­ creasing pH. At pH 8.0 uptake rate is extremely low, even at high ABA concentrations. This indicated that nearly all o f the ABA is taken up as the undissociated m olecule ABAH. Uptake o f ABA is influenced by agents m odifying the pH gradients between the m edium and the tissue such as salts o f weak acids incubated at low external pH (inhibition o f uptake and stim ulation o f ABA release by abolishing the pH gradients), protonophores such as CCCP (inhibition o f uptake) and fusicoccin (stim ulation o f uptake by increasing the pH between m edium and cytoplasm). It is concluded that ABA distributes between the compartments o f the root cells according to the pH gradients with the undissociated m olecule as the only penetrating species. Uptake and release occur without participation o f a saturable com ponent by diffusion. In contrast IAA permeates the plasm alem m a as both IAAH and IAA-. 
  Reference    Z. Naturforsch. 38c, 719 (1983); received March 31 1983 
  Published    1983 
  Keywords    Abscisic Acid, Diffusion, Indole Acetic Acid, Phaseolus coccineus, Plasm alem m a, Transport 
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 TEI-XML for    default:Reihe_C/38/ZNC-1983-38c-0719.pdf 
 Identifier    ZNC-1983-38c-0719 
 Volume    38