Isolation and structure of a new organic acid accumulated in tulip plant (Tulipa gesneriand)

A large quantity of an unidentified organic acid was detected in the tulip leaves and stems. The compound was identified as 2-oxo-4-methyl-3-pentene-1,5-dioic acid mainly based on 1H- and 13C-NmR spectra. This organic acid was present in the leaves and stems at a high concentration (ca. 10% of dry weight maximum). It was also detected in the flowers and daughter bulbs, but not in the roots, mother bulb and the basal plate. The organic acid content in the stem increased after sprouting of the plant, and it rapidly decreased immediately before flowering. On the other hand, the leaves continued to accumulate the acid until the flowering stage, and the level did not decrease thereafter until harvesting.