Resistance of cereals to aphids: the interaction between hydroxamic acids and glutathione S-transferases in the grain aphid Sitobion avenae (F.) (Hom., Aphididae)
1992
Leszcynski, B. (East Anglia Univ., Norwich (United Kingdom). School of Biological Sciences) | Dixon, A.F.G.
The activity of glutathione S-transferases in the grain aphid, Sitobion avenae (F.) was associated with the concentration of hydroxamic acids in the host plant of artificial diet. The grain aphid showed a higher level of activity of these enzymes when fed on moderately resistant wheat varieties than on susceptible ones. There was a high positive correlation (r = 0.869, P below 0.05) between the glutathione S-transferases activity in the aphids and the total quantity of DIMBOA (glucoside plus aglucone) in the tips of their host seedlings. DIMBOA-aglucone incorporated into a chemically defined diet generally decreased the activity of these enzymes. Relative to the control diet the greatest reduction in activity was observed at the low concentrations (0.01 mM - 0.1 mM) of DIMBOA-aglucone studied. The lower reduction in activity of the glutathione S-transferases observed at the higher concentrations (0.5 mM - 0.1 mM) of this allelochemical possibly resulted because at these concentrations it acts as a feeding deterrent. The interaction between the hydroxamic acids in winter wheat and the activity of the grain aphid's glutathione S-transferases as discussed
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