Scaling is a common commercial technique to propagate Lilium. The present research work evaluated the impact of genotype, traumatic acid (TA), and initial bulb quality on bulblet production by scaling propagation. Genotypes used were: L. longiflorum Thunb. `Snow Queen', L. lancifolium Thunb., one Oriental hybrid (L. × `Stargazer'), and four Asiatic hybrids (L. × `Enchantment', L. × `Connecticut King', L. × `Sunray', L. × `Cote d'Azur'). The genotypes showed a wide variability in the number (1.1-2.6 bulblets per scale) and biomass (83-295 mg per bulblet) of bulblet production. The same variability was exhibited after treatment with TA, which produced an increase of 20% to 40% in the number of bulblets per scale and also a significant increase in their fresh mass (20% to 60%). Using poor quality L. × `Cote d'Azur' bulbs adversely affected the biomass and number of bulblets produced on the scales, and this effect was not overcome with TA treatment. Chemical name used: 10(E) dodeca-l,12-dicarboxylic acid (traumatic acid).
Pablo Marinangeli and Néstor Curvetto
Pablo Marinangeli and Nestor Curvetto
Micropropagation is an advantageous technique for commercial Lilium propagation. The aim of this work was to evaluate the impact of genotype, traumatic acid [TA, 10(E) dodeca-1,12-dicarboxylic acid] treatment and an initial bulb quality on lily in vitro propagation. Genotypes were: L. longiflorum Thunb. `Snow Queen', L. lancifolium Thunb., one Oriental hybrid (L. × `Stargazer'), and four Asiatic hybrids (L. × `Enchantment', L. × `Connecticut King', L. × `Sunray', L. × `Cote d'Azur'). Assays were done with good-quality bulb genotypes—chosen by water content, sprouting degree, and appearance—with exception of L. × `Cote d'Azur', where poor-quality bulbs were also included. Surface-sterilized 3-mm scale bulb sections where cultured in MS medium with 100 mg·l–1 myo-inositol, 0.4 mg·l–1 thiamine·HCl, 0.1 mg·l–1 NAA, and 3% sucrose and 0.8% agar, pH 5.7. Cultures were kept in darkness at 25°C during 8 weeks. One μM TA was used to immerse half of the explants during 1 hr before culturing. Genotypes showed a wide variability in bulblets' number (1.7–2.9 bulblets per explant) and biomass (55–147 mg per bulblet). The same variability was observed after TA treatment, which produced an increase in bulblets number per explant (14% to 59%) and also a significantly augmented their fresh mass (9% to 42%). Poor-quality L. × `Cote d'Azur' bulbs adversely affected both biomass and number of bulblets produced on the scale sections, which was not overcome with TA treatment. These results suggest the convenience of TA application in Lilium micropropagation protocols on good-quality bulbs, irrespective to the genotype source.
Pablo Marinangeli, Silvia Delmastro and Néstor Curvetto
Both dibutyryl-cAMP and forskolin, with and without a pretreatment with traumatic acid, stimulated bulbing in vitro of Lilium longiflorum Thunb. by up to 65% over the controls. Dibutyryl-cAMP, forskolin, their combinations with traumatic acid, and adenosine significantly increased the micropropagation yield. Traumatic acid alone produced similar results on bulblet number per explant, but with increased fresh mass per bulblet. Chemical names used: 9-ß-D-ribofuranosyladenine (adenosine); adenosine 3′, 5′ - cyclic monophosphate (cAMP); dibutyryl adenosine 3′, 5′ - cyclic monophosphate (DB-cAMP); 9-ß-L (+) adenosine or 9-ß-L (+) ribofuranosyladenine; forskolin; 10(E) dodeca-1,12-dicarboxylic acid (traumatic acid).
Pablo A. Marinangeli, Luis F. Hernández, Cecilia P. Pellegrini and Néstor R. Curvetto
External, middle and inner scales in parent bulbs were studied to evaluate bulblet differentiation in Lilium longiflorum Thunb. during scale propagation at 25 °C. A 13-stage developmental process describes different steps including preprimordial, primordial, and bulblet formation. For all scales, preprimordial and primordial stages occurred within the first 4 days. The differentiation process depended on parent scale position. Most bulblets arising from external scales developed three true scales after 30 days while bulblets from middle scales formed four true scales. Homogeneity in the morphology of the parent scales, only shown in the middle ones, was associated with a rapid change in developmental stage for the population of bulblets. Inner scales showed few bulblets with three and four true scales, the rest remaining at earlier developmental stages. Bulblet production decreased from external to internal scales: 2.6, 2.2, and 1.2 bulblets per scale, respectively, and showed a positive correlation with the scale base width. Maximum scale weight and surface area and maximum bulblet fresh and dry weight occurred in the middle scales. We conclude that middle scales are the ideal starting material for experimental uses involving scaling propagation. For production purposes, the external scales, in addition to the middle scales, must also be included for propagation.