Studies of herbicide toxicity and mode of action using isolated mesophyll cells and callus-derived cell suspensions

Abstract

Enzymatically isolated mesophyll cells of peanut (Archis hypogeae L.) and callus-derived cell suspensions of peanut and soybean (Glycine max (L.) Merrill) were assessed for their usefulness in studies of the toxicity and (or) mode of action of two bipyridilium herbicides (diquat and paraquat) and of perfluidone. Isolated mesophyll cells were very useful for rapid analyses of photosynthetic inhibition by 1 or 10 μM concentrations of the bipyridiliums. Cells treated with perfluidone were not affected. The growth of nonphotosynthetic callus-derived peanut cell suspensions was inhibited strongly either in the light or in the dark at 1 and 10 μM concentrations of either bipyridilium compound. Growth was slowed in cells treated with 0.1 μM diquat but not paraquat. In contrast, callus-derived soybean cell suspensions grew well in 1 μM diquat or paraquat; 10 μM of either herbicide strongly inhibited growth.Ultrastructural analyses of isolated mesophyll cells were of limited usefulness in assessing herbicide toxicity and mode of action because both untreated and treated enzymatically isolated peanut mesophyll cells had damaged membranes with extensive lipid deposits. In contrast, callus-derived soybean cell suspensions of both treated and untreated cells were undamaged for up to 6 days so that reduced growth of the cultures was not caused by destruction of organelles.

Behavior of BAS-9052 OH in Soybean (Glycine max) and Johnsongrass (Sorghum halepense) Plant and Cell Cultures

“…Technical 4-14 C-BAS-9052 OH was obtained with specific activity of 13.9 mCi/mmol 5 . Immediately prior to application, a stock solution of 1 4 C-BAS-9052 OH containing 3.25 /iCi/ml was prepared in a volume of 1 ml of water containing 1% crop oil 6 , or in 1 ml of hexane. A microliter pipet calibrated to deliver 2 -fdl droplets was used to apply 0.16 fiCi (4.0 /ig) of 1 4 C -BAS-9052 OH/plant in a total volume of 50 /il.…”

“…Presently, investigators are also using highly purified, cell-free extracts to study herbicidal phytotoxicity and mechanisms of action. The gap between isolated enzyme systems and whole plants is being increasingly filled by studies utilizing algae (12), mechanically or enzymatically isolated cells (6), and undifferentiated cell suspensions derived from callus tissue (6,10,17,20,21). Callus -derived cell suspen sions can be maintained for long periods of time and provide an axenic system that is easily manipulated (6,10,21).…”

Detoxification of chlorotoluron in a chlorotoluron‐resistant biotype of Alopecurus myosuroides. Comparison between cell cultures and whole plants

“…Cell cultures of a variety of plant species have been u.sed since the early 198()s to study the metabolism of xenobiotics (Davis and Shimabukuro 1980). These systetn s have some advantages over whole plants when studying herbicide tnetabolistn, such as (1) their relative hotnogeneity when they ate used at an appropriate gtowth phase (Sterling and Baike 1988), (2) a reduced content of pigtnents that can facilitate analytical measurements as they mask results (Matringe et al 1990), (3) the avoidance of absorption and translocation barriers in species in which they complicate metabolism studies (Lamoureux et al, 1991) and (4) their insensitivity to photosynthesis-inhibiting herbicides (as they are nonchlorophyllous cultures), allowing herbicide metabolistn to be evaluated in the absence of phytotoxicity (Grosstnann et al 1992).…”