Plant Growth Regulation

, Volume 16, Issue 3, pp 215–231

Phloem mobility of xenobiotics: tabular review of physicochemical properties governing the output of the Kleier model

  • A. J. P. Brudenell
  • D. A. Baker
  • B. T. Grayson

DOI: 10.1007/BF00024777

Cite this article as:
Brudenell, A.J.P., Baker, D.A. & Grayson, B.T. Plant Growth Regul (1995) 16: 215. doi:10.1007/BF00024777


The Kleier model of phloem-mobility of xenobiotics combines the intermediate permeability hypothesis with the acid trap mechanism for weak acids. The output of the model is dependent on the lipophilicity of a compound, for which octanol/water partition coefficients (log Kow) have been used as a measure. The membrane permeability of xenobiotics is predicted from these partition coefficients, and the nature of the sieve tube membranes has been modelled using regressions derived from Nitella or potato permeability data. A wide range of log Kow values for herbicides, fungicides, insecticides and experimental compounds (≈400) have been tabulated along with the model output for various membrane parameters. The application of the model is in broad agreement with literature and experimental observations on many of the known phloem mobile herbicides and predicts low phloem mobility for the fungicides and insecticides considered here, again in agreement with the literature. The behaviour of herbicides representative of the main chemical families and modes of action are reviewed, along with examples of the few phloem-mobile fungicides and insecticides identified.

Key words

acid trap herbicides partition coefficient pesticides phloem transport xenobiotics 



octanol-water partition coefficient


−log10 acid dissociation constant


Concentration factor


membrane permeability

Copyright information

© Kluwer Academic Publishers 1995

Authors and Affiliations

  • A. J. P. Brudenell
    • 1
  • D. A. Baker
    • 1
  • B. T. Grayson
    • 2
  1. 1.Department of Biological Sciences, Wye CollegeUniversity of LondonAshfordUK
  2. 2.Biological Evaluation Division, Sittingbourne Research CentreShell Research Ltd.SittingbourneUK
  3. 3.Department of Biology, Silwood ParkImperial CollegeAscot
  4. 4.School of Biological ScienceUniversity of PortsmouthPortsmouthUK

Personalised recommendations