Hydroxycinnamoyl amides in stem explants from flowering and non‐flowering Nicotiana tabacum

Flower formation in stem explants was chosen as an experimental system for the study of the function of hydroxycinnamoyl amides (HCAs) in plants. The explants, derived from flowering and non‐flowering Nicotiana tabacum L. var. Xanthi nc., differentiated to two types of callus and afterwards to flower buds. A novel reversed‐phase high performance liquid chromatography method, following sample clean‐up on CM‐Fractogel columns, enabled us to examine HCA concentrations in small tissue samples. Two different groups of HCA could be distinguished during in vitro flower formation: Firstly, feruloyl‐ and diferuloyputrescine, the major detectable HCAs that accumulated during callus proliferation; secondly, caffeoylputrescine, which accumulated during the later stage of flower differentiation and reached higher concentrations than feruloylputrescine.