Figure 6.

Observed and predicted labeling pattern of IAA. Predictions are made on the basis of metabolites derived from kernels labeled with [U-¹³C₆]Glc. 1, Prediction for a Trp-dependent IAA biosynthesis. 2, Prediction for a hypothetical pathway via indole and a C2 metabolite derived from acetyl-CoA. 3, Prediction for a hypothetical pathway via indole and a C3 metabolite derived from PEP or triose-P. 4, Prediction for a hypothetical IAA biosynthesis directly from IGP, the isotopomer composition of which can be deduced from anthranilate and Rib. Contiguous ¹³C labeling is shown by bold lines and the normalized abundance of the isotopomer is given (Tables II and III).