EFFECT OF REPEATED SEVERE PRUNING ON ENDOGENOUS POLYAMINE CONTENT IN HAZELNUT TREES

Endogenous polyamine content was determined in leaves and buds of adul t and repeatedly severe pruned hazelnut trees (Corylus avellana L.). P olyamine content in leaves from shoots obtained by forced outgrowth of branches taken from adult and pruned trees was also determined. Varia tions of polyamine levels in relation to pruning treatments were obser ved in all the analysed tissues. Free polyamines increased in response to pruning treatments, mostly due to an increase in free putrescine. Free spermidine and spermine seemed to decrease with pruning intensity , whereas bound polyamines did not seem to correlate with treatments. Significantly, in all the analysed tissues the putrescine to spermidin e plus spermine ratio increased in the free polyamine fraction. The re sults indicate that polyamine metabolism could play a role as a physio logical marker for juvenility and rejuvenation in relation to cloning of woody plants. The possible role of polyamines in mediating and/or r egulating phase change and reinvigoration is discussed.