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Characterization of hydrophilic and lipophilic pathways of Hedera helix L. cuticular membranes: permeation of water and uncharged organic compounds.
- Source :
- Journal of Experimental Botany; Nov2005, Vol. 56 Issue 421, p2797-2806, 10p
- Publication Year :
- 2005
-
Abstract
- The permeability of astomatous leaf cuticular membranes of Hedera helix L. was measured for uncharged hydrophilic (octanol/water partition coefficient log KO/W ≤0) and lipophilic compounds (log KO/W >0). The set of compounds included lipophilic plant protection agents, hydrophilic carbohydrates, and the volatile compounds water and ethanol. Plotting the mobility of the model compounds versus the molar volume resulted in a clear differentiation between a lipophilic and a hydrophilic pathway. The size selectivity of the lipophilic pathway was described by the free volume theory. The pronounced tortuosity of the diffusional path was caused by cuticular waxes, leading to an increase in permeance for the lipophilic compounds after wax extraction. The size selectivity of the hydrophilic pathway was described by hindered diffusion in narrow pores of molecular dimensions. A distinct increase in size selectivity was observed for hydrophilic compounds with a molar volume higher than 110 cm3 mol−1. Correspondingly, the size distribution of passable hydrophilic pathways was interpreted as a normal distribution with a mean pore radius of 0.3 nm and a standard deviation of 0.02 nm. The increased permeance of the hydrophilic compounds by the removal of cuticular waxes was attributed to an increase in the porosity, a decrease in the tortuosity, and a widening of the pore size distribution. Cuticular transpiration resulted from the permeation of water across the hydrophilic pathway. The far-reaching implications of two parallel pathways for the establishment of correlations between cuticular structure, chemistry, and function are discussed. [ABSTRACT FROM PUBLISHER]
- Subjects :
- ENGLISH ivy
ORGANIC compounds
ORGANIC chemistry
MOLECULAR volume
PLANT protection
Subjects
Details
- Language :
- English
- ISSN :
- 00220957
- Volume :
- 56
- Issue :
- 421
- Database :
- Complementary Index
- Journal :
- Journal of Experimental Botany
- Publication Type :
- Academic Journal
- Accession number :
- 44577463
- Full Text :
- https://doi.org/10.1093/jxb/eri272