CHANGES IN SHIKIMATE DEHYDROGENASE AND THE END-PRODUCTS OF THE SHIKIMATE PATHWAY, CHLOROGENIC ACID AND LIGNINS, DURING THE EARLY DEVELOPMENT OF SEEDLINGS OF CAPSICUM-ANNUUM

The developmental regulation and organ-specific expression of shikimat e dehydrogenase was studied in seedlings of Capsicum annuum L. during their early development. The results obtained suggest that there is bo th a developmental regulation and an organ-specific expression of shik imate dehydrogenase in seedlings of C. annuum, seen mainly in the coty ledons. For example, shikimate dehydrogenase isoenzyme 3 was different ially expressed in cotyledons, but not at all in roots or hypocotyls. When the amounts of shikimate dehydrogenase were compared with the end -products of the shikimate pathway, chlorogenic acid and lignins, it w as observed that the fall in shikimate dehydrogenase activity in cotyl edons coincided with a decrease in the concentrations of phenolics dur ing primary leaf development. However, this did not seem to be the cas e with the hypocotyls, where the fall in phenolics was not related to the amount of shikimate dehydrogenase but rather to an increase in lig nin deposition, supporting the view that chlorogenic acid might act as a precursor of the aromatic moiety of cinnamoyl alcohols during cell wall lignification.