Abstract
Aconitic acid was observed to be a prevailing substance in acid-soluble components of wheat (8 lines), corn (10 lines), sorghum (2 lines) barnyard grass (3 subspecies) and rice (1 line). In barley it was present in rather small and inconsistent amounts (8 lines). We studied possible relationship between aconitic acid and degree of resistance or susceptibility to aphids. Corn, a line of sorghum and a mature stage of a subspecies of barnyard grass contained between 200 and 600 μg of aconitic acid/g, and seemed to be highly resistant. Between 100 to 200 μg/g were found in other subspecies of barnyard grass, a rice line and a susceptible line of sorghum. Ten to 25 μg/g were found in wheat. Some lines of wheat showed weak resistance while others were susceptible. Aconitic acid may play a role in the resistance of some cereals to aphids.
