A phytochrome-mediated alteration from stem to rosette growth on chicory root explants in vitro

Chicory root explants (Cichorium intybus L. var. foliosum) of two cultivars, taken before and after hydroponic forcing, were cultured in vitro in complete darkness supplemented with red and far-red light treatments. Using 5 min red light per day, the strong stem elongation occurring in complete darkness was converted to rosette formation. This reaction was reversed to stem elongation (accompanied by leaf formation) adding 15 min far-red light after the red light. Fifteen min far-red light per day alone caused the same reaction as 5 min red/15 min far-red light. Far-red light followed by red light caused rosette formation. In stems, formed under complete darkness in vitro, the presence of phytochrome was shown. No phytochrome was detected in the root fragment itself.Abbreviations R red light - FR far-red light - GA gibberellinic acid - A absorbance - FW fresh weight