The physiological consequences of ethylene glycol-induced changes in the frond structure of Lemna gibba

Abstract

Ethylene glycol is the major component of many antifreeze/coolant and deicant formulations. Its use as an aircraft/runway deicant ensures that it is a major but intermittent pollutant of surface waters in the vicinity of those airports where it is used. Other uses, such as in automobile radiators or as a hydraulic fluid, result in smaller but more continuous and widespread releases. However, ethylene glycol is usually thought of as being relatively benign and therefore its fate and effects in higher plants have received little attention. Using axenic cultures of the aquatic angiosperm, Lemna gibba (duckweed), it has been shown that while ethylene glycol is not metabolized and is relatively non-toxic as far as vegetative reproduction in duckweed is concerned (EC 10 and EC 50 were 5740 and 10 920 ppm, respectively), it does have dramatic effects upon the structure of young fronds during their early growth and development. The result of the changes in frond structure is to increase the uptake of water and solutes from the surrounding environment. It is suggested that an increase in the uptake of a nutrient can lead to enhanced growth whereas an increase in the uptake of a toxicant can lead to the potentiation of its toxicity. In either case, the ecological consequences could be profound.