Polyamines and hyperhydricity in micropropagated carnation plants

Changes in polyamine (PA) levels and patterns were studied in response to hyperhydricity in micropropagated carnation plants. Hyperhydric carnation leaves showed high peroxidase activity, low lignification and high malondialdehyde (MDA) content, suggesting oxidative damage. The most predominant fraction of PA corresponded to free PA in hyperhydric leaves as well as in control non-hyperhydric leaves. Regarding individual amines, hyperhydricity brought about an almost complete depletion of free 1,3-diaminopropane (Dap), a rise in the conjugated form of this amine, and a great reduction in bound spermidine (Spd) in relation to non-hyperhydric leaves. A very high percentage (up to 80%) of reverted shoots was obtained by maintaining hyperhydric carnation shoots in a culture chamber with a bottom-cooling device that lowered the RH inside the culture jars. Reversion of hyperhydricity was associated with changes in PA patterns. Thus, compared with both non-hyperhydric and hyperhydric leaves, reverted plants showed a drastic reduction in free PA, and a major increase in conjugated diamines (especially important in the case of cadaverine, Cad). The PA profile in non-hyperhydric and hyperhydric plants could indicate stress condition and a more suitable physiological situation in reverted plants. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.