Endogenous polyamine concentrations in juvenile, adult and in vitro reinvigorated hazel

We investigated endogenous polyamine concentrations in leaves from juvenile and mature hazel (Corylus avellana L.) shoots, as well as leaves from shoots obtained by both forced outgrowth and micropropagation of adult tissues. To determine if the observed in vitro reinvigoration was associated with polyamine metabolism, we tested the effect of serial subcultures on polyamine concentrations. Polyamines, mostly free putrescine, were higher in juvenile tissues. Adult tissues micropropagated for 14 subcultures had polyamine concentrations characteristic of juvenile tissues. However, with additional subcultures, total polyamine concentrations decreased. The putrescine to spermidine plus spermine ratio was higher in juvenile and micropropagated tissues than in adult tissues, but decreased in micropropagated tissues after 20 subcultures. This ratio may reflect a balance between vegetative growth and reproductive processes. Thus, an analysis of polyamine concentrations may provide a simple assay for determining the juvenility of plant tissues and, hence, their suitability for micropropagation.