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Metaboliti secondari ad attività antitumorale in Camptotheca acuminata Decne, e loro localizzazione cellulare.
No full textPhotomorphogenic effect of red light on de novo flower formation from tobacco thin layers
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Cellular localisation of the anti-cancer drug camptothecin in Camptotheca acuminata Decne (Nyssaceae)
No full textIn Camptotheca acuminata, we studied the cellular sites of accumulation of the alkaloid camptothecin (CPT), in both plants grown in the field and those grown in a greenhouse, subjecting the latter to stress (i.e., draught, nutritional deficit, and pruning). Fresh sections of the leaf, stem, and root were analysed for the presence of CPT by examining the autofluorescence that the CPT molecule emits when exposed to UV radiation. In the plants grown in the field, CPT was observed only rarely. In the greenhouse plants, CPT had accumulated in crystalline form in the vacuole of specialised cells (i.e., segregator idioblasts), which were not morphologically distinguishable from the cells of the surrounding tissues. In the organs examined, the segregator idioblasts were localised in parenchymatic and epidermal tissues. CPT crystals were also detected in the glandular trichomes on both the stem and leaf
INVITRO FLORAL MORPHOGENESIS IN A DOUBLED HAPLOID TOBACCO
No full textThin cellular layers of epidermal, subepidermal and cortical tissues were taken from floral pedicels and peduncles of the unripe infructescences of Nicotiana tabacum cv. White Burley doubled haploid plants. These plants belong to an isogenic line with abundant in vivo flowering, and their pedicel explants show in vitro, compared with those of amphidiploid control, a higher capacity to differentiate flowers in a short period of time and in the near or complete absence of vegetative competition. These results may provide elements for using suitably selected doubled haploid plants in order to study floral differentiation and its genetic control. © 1986
Different phases of the reproductive process in Nicotiana tabacum plants quantitatively affect floral and vegetative neoformation in vitro
No full textTHE EFFECT OF PHOTOPERIOD ON FLOWER FORMATION INVITRO IN A QUANTITATIVE SHORT-DAY CULTIVAR OF NICOTIANA-TABACUM
No full textSuperficial cell layers of a quantitative short-day tobacco plant (Nicotiana tabacum L. cv. White Burley) were excised from different parts of the inflorescence (i.e. pedicels, branch internodes, rachises), and cultured in continuous darkness, continuous light or 8 h light/16 h dark daily. The flowering response in vitro of the different types of explants was investigated with respect to the effect of light on the post-evocation phases of the flowering process and explant commitment. Treatment effect was qualitatively and quantitatively influenced by explant origin. Three morphogenic features were observed: flower neoformation, caulogenesis and rhizogenesis (the latter on rachis explants only). Under all treatments, the highest flowering potential was shown by pedicels, while the highest vegetative potential was shown by rachises. Branch internodes showed an intermediate response, but with a tendency towards caulogenesis, which probably reflects their phylogenetic origin. Thus, opposite gradients of the neoformation of flowering and vegetative buds on explants were observed under all treatments. Pedicels formed new single flowers rather than inflorescences, while rachises regenerated mainly inflorescences. In darkness, flowering was limited mostly to pedicels. Vegetative bud formation was higher than floral bud regeneration in all types of explant. Continuous light enhanced the flowering response mostly in pedicel and branch internode explants. Short days enhanced flower bud formation in vitro on all types of explant. Results with respect to microsporogenesis, flower and inflorescence anomalies observed under darkness also seem to support the existence of a quantitative photoperiodic control on floral neoformation in vitro in this plant. These results suggest that in Nicotiana tabacum cv. White Burley in vivo floral induction, initiation and development are governed by the same photoperiodic requirements
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