Journal of Experimental Botany, Vol 49, 115-123, Copyright © 1998 by Oxford University Press
The impact of ozone, isoprene and propene on antioxidant levels in two leaf classes of velvet bean (Mucuna pruriens L.)
N Stokes, G Terry and C Hewitt
Institute of Environmental and Natural Sciences Lancaster University, Lancaster LA1 4YQ, UK; Corresponding author e-mail: n.stokes@lancaster.ac.uk
Four-week-old velvet beans (Mucuna pruriens L.) were
fumigated with ozone, isoprene and propene both singly and in combination
(hydrocarbon+oxidant) in controlled-environment chambers for a 4 week
period. Measurements were made of total soluble protein, ascorbate,
dehydroascorbate, lipid peroxidation, and glutathione reductase activity in
mature and young velvet bean leaves.Significant increases in soluble
protein concentrations with respect to the controls were found in plants
fumigated with propene and isoprene+ozone for young leaves, and ozone only
for mature leaves. The analysis of ascorbate concentrations in young leaves
showed a significant increase in total ascorbate for propene-fumigated
plants a significant decrease in the level of the oxidized form
(dehydroascorbate) for ozone and isoprene+ozone-treated plants, and a
significant increase in the reduced form for plants fumigated with propene,
propene+ozone and isoprene+ozone. The analysis of ascorbate levels in
mature leaves showed no significant effect from any fumigation regime.When
compared to control material the specific activity of the enzyme
glutathione reductase was found to be significantly reduced in young leaves
treated with propene, isoprene+ozone and ozone alone. However, in mature
leaves this effect is lost and there are no significant differences with
respect to the control.Key words: Ozone, hydrocarbons,
velvet bean, Mucuna pruriens, antioxidants.