Planta

, Volume 206, Issue 2, pp 322–328

Differences among plant species in cuticular permeabilities and solute mobilities are not caused by differential size selectivities

Authors

  • Anke Buchholz
    • Institut für Gemüse- und Obstbau, Abteilung Obstbau, Universität Hannover, Am Steinberg 3, D-31157 Sarstedt, Germany
  • Peter Baur
    • Institut für Gemüse- und Obstbau, Abteilung Obstbau, Universität Hannover, Am Steinberg 3, D-31157 Sarstedt, Germany
  • Jörg Schönherr
    • Institut für Gemüse- und Obstbau, Abteilung Obstbau, Universität Hannover, Am Steinberg 3, D-31157 Sarstedt, Germany
Article

DOI: 10.1007/s004250050407

Cite this article as:
Buchholz, A., Baur, P. & Schönherr, J. Planta (1998) 206: 322. doi:10.1007/s004250050407

Abstract.

Solute mobilities in cuticular membranes of six species (Hedera helix, Malus domestica, Populus alba, Pyrus communis, Stephanotis floribunda, Strophantus gratus) were measured using plant hormones, growth regulators and other organic model compounds varying in molar volumes from 99 to 349 mL · mol−1 The dependence of mobilities (k*) on molar volume (Vx) was exponential and could be described with equations of the type logk*=logk*0Vx. The y-intercepts (logk*0) represent mobilities of a hypothetical solute of zero molar volume. The parameter β′ is a measure of size selectivity of cuticular membranes and no differences among the six species were observed. At 25 °C the average β′ was 0.0095 mol · mL−1. Solute mobility decreased by about a factor of 8.9 when molar volume increased by 100 mL · mol−1 and the mobility of a compound with Vx = 100 mL · mol−1 was about 700-fold higher than the mobility of a compound with Vx = 400 mL · mol−1. Size selectivity decreased with increasing temperatures and for Strophantusβ′-values of 1.6 × 10−2 to 8.0 × 10-4 mol · mL−1 were obtained for 10 and 30 °C, respectively. The-intercepts (log k*0) differed among plant species by 3 orders of magnitude and since size selectivity was the same for all species, solute mobilities for solutes having zero molar volumes were the sole cause for differences among species in solute mobilities and permeabilities. We argue that these differences in k*0 are related to tortuosity of the diffusion path. These results were used to derive an equation which predicts rates of cuticular penetration on the basis of k*0, the average size selectivity of 9.5 × 10−3 mol · mL−1 and the driving forces of penetration.

Key words: Cuticular membraneFoliar uptakeGrowth substance Membrane permeabilitySize selectivity (cuticle)Solute mobility

Copyright information

© Springer-Verlag Berlin Heidelberg 1998