When corn (Zea mays) roots are supplied with high concentrations of unlabeled myoinositol, the conversion of d-glucose-6-(14)C to cell wall galacturonic acid is significantly reduced compared to controls, although its incorporation into cell wall glucosyl units remains unchanged. This suggests that, in order to be converted to uronic acid, radiolabel from glucose must first pass through the internal myoinositol pool of the roots.