Role of Aconitate Isomerase in trans-Aconitate Accumulation in Plants

Wheat seedlings ( Triticum aestivum ) grown on single salt solutions were analyzed for trans- aconitate and aconitate isomerase to determine the possible relationship between them and to determine if they might be related to the incidence of grass tetany. The trans- aconitate activity at the end of a two-day growth period and changes in trans- aconitate activity during this period varied widely and were related to the cation but not the anion of the single salt solution. Aconitate isomerase activity did not vary as much as trans- aconitate or change in trans- aconitate content, and was not closely correlated with the trans- aconitate content. Analysis of diverse species and tissues for aconitate isomerase and trans- aconitate showed that the presence of aconitate isomerase was necessary for appreciable trans- aconitate accumulation. We conclude that the activity of aconitate isomerase does not control trans- aconitate content but that its presence is necessary for any significant accumulation of trans- aconitate.