Feruloyl‐ and caffeoylputrescine in stem explants from photoperiodically determined Nicotiana species

Abstract

The distribution and formation of hydroxycinnamoyl amides (HCA) in in vitro grown stem explants from day‐neutral Nicotiana tabacum L. var. Xanthi no were investigated using [14C]‐labelled precursors. Feruloylputrescine (FP) (labelled from [14C]‐putrescine) was continually formed with a decreasing formation rate during a culture period of 35 days. The specific radioactivity, however, remained constant. In contrast, caffeoylputrescine (CP) was labelled in the second part of culture only. [UC]‐Label from putrescine, spermidine, spermine, and cinnamic acid was incorporated into FP and p‐coumaroylspermidine. CP was labelled from [14C]‐putreseine and [14C]‐spermidine only, while diferuloylputrescine (diFP) failed to be labelled by any of the precursors used. Tissue investigations showed that FP is dominant in cortex during formation of cortical callus, while CP showed a sequential gradient from pith to cortical callus to floral buds. Experiments with photoperiodical Nicotiana species were used to investigate the pattern of HCAs in induced and non‐induced plants. The origin of explants had no influence on the pattern of FP and CP but resulted in different growth responses. FP is a marker of cortical callus formation in all explants. CP does not trigger the growth processes observed in the expants since CP also increased in photoperiodically non‐induced explants of tobacco, which stopped growing after the formation of cortical callus.