Effect of herbicides on cell membrane permeabUity in Lemna minor

Abstract

Summary: Leakage of electrolytes was the criterion used to study the effects of several herbicides on cell membrane permeability in Lemna minor L. Dinoseb. sodium azide, linuron, prometryne and simazine were the most active in increasing cell membrane permeability, followed by oxyfluorfen, amitrole, and 2,4—D. Glyphosate and dalapon were the least active. In all cases, the longer the period elapsed after treatment (i.e. 96 h) the lower was the concentration needed to alter cell membrane permeability. Light was necessary for oxyfluorfen activity. With glyphosate, dalapon and oxyfluorfen, visible injury symptoms were noted after 48–96 h, but no further significant increase in cell membrane permeability occurred as a result.

Herbicide Effects on Liposome Leakage

“…Other research, however, has reported that diphenyl ethers (such as nitrofen) and triazines can cause plant cell leakage (12,13,14), but the activity of these compounds appears reciprocating water bath operated at 120 excursions/min with a 3 -em throw. After a specified time the dialysis sacks were removed from the vials, and the absorbance of the contents was determined at 370 nm.…”

“…However, increased leakage in the presence of an added chemical is not in itself evidence of a direct interaction with cell membranes. Cyanide (4,5), a non -lipophilic respiratory inhibitor, azide (12), and anaerobiosis (5) also promote cell-membrane leakage. These events are not governed by direct interactions with cell membranes, and they oppose the simple interpretations that often accompany leakage data.…”

“…In investigating herbicidepromoted permeability of living plant cells, it is often impossible to discern whether leakage results from direct interaction of the herbicide with cell membranes, or whether the response is secondary, arising from impairment of a basic metabolic system. For example, it is well established that respiratory inhibition is accompanied by increased cell permeability (4,5,12,18). The herbicides MCPB, 2,4,5 -T, ioxynil, PCP, and barban, all of which caused leakage in tobacco tNicotiana tabacum L.) cell suspensions (18), have been characterized as having activity as respiratory inhibitors (7,8,9,16,21).…”