Plant Translocation of Organic Compounds: Molecular and Physicochemical Predictors

Abstract

The root-soil boundary represents one of the largest global biotic-abiotic mass-transfer interfaces and is a primary pollutant entry point to the food chain. This interface is also critically important in phytoremediation efforts and herbicide design. Experimental data and single-parameter models have resulted in the current understanding that moderately hydrophobic organic compounds are most likely to be translocated by plants, although recent evidence indicates plants can also translocate some hydrophilic compounds. Molecular descriptors initially applied for drug discovery and for transmembrane migration in mammalian systems were applied here to determine the physicochemical domains and weighted desirability functions to identify compounds amenable to translocation by plants. Considering molecular descriptor cutoffs defined in this work, chemicals likely to be translocated by plants more closely resemble those that can cross the blood-brain barrier as compared to the intestine. Desirability functions were also used to generate quantitative estimates of plant translocation, and these results revealed similarities to the human system, as well. Knowledge of the physicochemical domain encompassing plant-translocatable contaminants from this work allows in silico screening of emerging contaminants for better estimates of exposure.