Horizontal Natural Product Transfer: A so far Unconsidered Source of Contamination of Plant-Derived Commodities

Abstract

It is well known that allelochemicals or xenobiotics such as systemic pesticides, veterinary remedies etc., are taken up by plants from the soil. However, information is lacking as to whether or not this uptake of organic compounds represents an isolated, singular event, or if it is a general phenomenon. Just recently, it was shown that nicotine, leached out from rotting tobacco into the soil, is taken up in the same manner. The question arises if other natural products, such as alkaloids, phenols or terpenes might be imported in the same manner. This may be particularly relevant for all the substances that are leached from decomposing plants. In this paper, the novel concept of “horizontal transfer of natural substances” based on the uptake of alkaloids derived from decaying plant materials is illustrated: after plant death, the soluble substances - including all natural products - are leached out from the decompartmented plant remains into the soil and are taken up by other plants. Related nutritional aspects as well as the significance of this phenomenon for our understanding of allelopathy are addressed.