Changes in peroxidase activity, and level of phenolic compounds during light-induced plantlet regeneration from Eucalyptus camaldulensis Dehn. nodes in vitro

Node cultures of Eucalyptus camaldulensis Dehn in Petri dishes in vitro und er darkness in the presence of an auxin developed meristematic agglomerates (4 to 6 diameter), i.e. dense shoot clusters in which outgrowth of numerou s successive buds is limited. Similar cultures under a 16 photoperiod produ ced small green plantlets with reduced leaves often presenting white hypert rophied lenticels and very short roots crowning the stem bases. The use of half-litre glass vials under light allowed direct development of well-devel oped rooted plantlets, either in the presence of the same auxin or in the p resence of a cytokinin. Light favoured an increase in phenolic compounds an d a reverse variation of peroxidase activity during the culture cycles. The se aspects are discussed in terms of a possible regulation of the endogenou s auxin level through a light control of peroxidase activity and the level of phenolic compounds.