ENHANCEMENT OF K plus UPTAKE THROUGH THE PLASMA-MEMBRANE IN FRESHLY CUT ROOT SEGMENTS FROM MAIZE SEEDLINGS PRETREATED WITH SPERMIDINE

An overnight pretreatment of maize seedlings with spermidine (SPD, 1 mM) induces a strong enhancement (approx. 100%) of K+ uptake through the plasma membrane in freshly cut root segments (To) and to lower extent (approx. 20%) in 2 h washed (W) root segments. The maximum effect is reached at 0.5 mM SPD concentration and after 12 h preincubation. Moreover the inhibition previously reported (de Agazio et al., Plant Physiol., 87 (1988) 176-178) exerted by SPD when applied to washed root segments, did not occur if seedlings were pretreated with SPD. The data suggest that the increase of K+ uptake in freshly cut root segments from seedlings pretreated with SPD, is partially due to a decrease of the inhibiting effect of cutting injury.