Herbaceous peony plants successfully propagated in vitro do not survive the transfer to the ex vitro environment. For other species, storage organ formation in vitro can limit the loss of plants during acclimatization. In the natural conditions, the renewal buds for the following year originate on the underground crown (metamorphosed underground shoot, rhizome) of herbaceous peony. A perennial crown and roots serve for the accumulation of the storage products and plant renewal. The aim of the experiment was to investigate the influence of glucose (30, 60 90 g l-1) and growth regulators (kinetin, IBA, GA3) on the shoot, renewal bud, root growth and development of Paeonia lactiflora 'Jadwiga' in vitro. Excision of all leaves from isolated explants inhibited production of new shoots and leaves, and evidently induced formation of renewal buds. Increasing the glucose supply, especially in the absence of growth regulators, decreased production of shoots and outgrowth of leaves. The stronger inhibition of shoot growth by glucose was observed on the explants without leaves. By contrast, the beneficial effect of glucose on renewal bud formation was observed. A single supply of kinetin, IBA or GA3 stimulated shoots and leaf growth and inhibited renewal bud formation, on the explants isolated with leaves. Interaction of kinetin, GA3 and IBA (added together) and the highest glucose level enhanced the growth of shoots on the explants containing leaves, and increased the number of renewal buds, on the explants without leaves. Increasing glucose level enhanced the number of roots in the absence of growth regulators on the explants containing leaves. The supply of IBA in the medium containing 30 g l-1 glucose, stimulated the root production on the explants without leaves. The addition of GA3 or kinetin (singly or simultaneously with IBA) to the medium with different concentrations of glucose, strongly inhibited rooting. Vol. 18(2) 2010: 309-320 The results presented here, show that a high level of glucose and exogenous growth regulators (kinetin, GA3, IBA) together stimulate shoot and renewal bud formation but the way of organogenesis depends on the presence or absence of leaves. The interaction between auxin (exogenous or endogenous) and glucose regulate root formation on the peony shoots but the final effect depends on the type of explants (with or without leaves). It is possible that leaves have a very important hormonal factors, which stimulate shoot growth or rooting and inhibit renewal bud formation.
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