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Asexual propagation in Ceratonia siliqua L. (carob), species of economic value, is difficult because of adventitious rooting recalcitrance. In Pinus radiata adventitious rooting of hypocotyl cuttings is enhanced by two urea-derivatives, 1,3-di(benzo[ d]oxazol-5-yl)urea (5-BDPU) and 1,3-di(benzo[ d]oxazol-6-yl)urea (6-BDPU), combined with exogenous indole-3-butyric acid (IBA). The research was aimed to define the role of these urea-derivatives in adventitious root (AR) formation of carob, and to identify morphogenic roles induced in carob, but also in pine, a distantly-related forest species. In carob, 5-BDPU (10 μM) highly promoted AR formation in combination with IBA (1 μM) when applied for 3 days, followed by a transfer onto hormone free medium (HF) up to culture end (4 weeks). IBA alone (1 μM) was more effective than IBA + kinetin (Kin, 10 nM), whereas Kin alone and 5-BDPU alone were not AR-inductive. The histological analysis showed that the cambial cells initiated the ARs, and similar numbers of AR-primordia were visible at day 12, independently of the AR-inductive treatment (i.e., IBA, IBA + 5-BDPU, IBA + Kin). No cutting treated with Kin alone, and rare HF (±5-BDPU)-treated ones, showed AR-primordia at day 12. The number of AR-forming explants increased under IBA + 5-BDPU. By contrast, the cambial cells were stimulated to initiate deuteroxylem instead of ARs under 5-BDPU alone. The histological analysis in pine microcuttings treated with IBA and/or 5-BDPU at the same concentrations confirmed that 5-BDPU applied alone enhanced xylogenesis, highlighting that this urea-derivative exhibits a dual morphogenic role being involved in the switching between adventitious rooting and xylogenesis depending on the presence of exogenous auxin in both species. [ABSTRACT FROM AUTHOR]

Hydrangea (Hortensia) is a highly popular ornamental plant for garden decoration, and now it is commercially produced for cut flower branches. For in vitro culture, Murashige and Skoog medium supplemented with BA (0.25 mg/L) and sucrose (30 g/L) was used. Culture conditions were 23 ± 1°C of temperature, light intensity of 35 μmol/m(2)/s P.P.F.D., and 16/8 h day/night photoperiod. Following shoot proliferation, the in vitro rooting frequency was 100% on a medium containing NAA 0.5 mg/L. However, 95% direct in vivo rooting was achieved by dipping microcuttings in a 5,000 ppm K-IBA solution which were transferred afterward to a glasshouse for acclimatization. After 21 days, fully acclimatized and well-established plants were obtained, suitable for commercialization. Furthermore, leaf fragments derived from in vitro plantlets were cultured for callus induction and adventitious shoot regeneration.