Regulation of organogenesis in small explants of superficial tissue of Nicotiana tabacum L.

Abstract

Small explants composed of 3-6 layers of epidermal and subepidermal cells excised from floral branches of Nicotiana tabacum are capable of de novo organogenesis. Continuous mitoses without organogenesis, or mitoses followed by the formation of floral buds, vegetative buds or roots can be obtained by varying the auxin-cytokinin-sucrose ratio in the medium. The physiological stage of the floral branches, and light and darkness had also an influence on the de novo organogenesis. Best floral-bud formation was obtained when explants were taken from plants in which the terminal bud was in the green-fruit stage, and were cultured on a medium with indole-3-acetic acid and kinetin both at 10(-6) M and with 3% sucrose, in the light. For differentiation of vegetative buds, the optimal auxin/cytokinin ratio was one tenth of that for floral-bud formation, while the sucrose concentration was the same. Optimal conditions for root formation were: explants from plants in which the terminal bud carried a mature fruit; 10(-7) M kinetin, 10(-5) M indole-3-butyric acid, and 1% sucrose in the medium; and culture in darkness. The optimal medium for callus formation contained 5×10(-6)M 2,4-dichlorophenoxyacetic acid, 10(-7) M kinetin and 3% sucrose.

Indole-3-butyric acid promotes adventitious rooting in Arabidopsis thaliana thin cell layers by conversion into indole-3-acetic acid and stimulation of anthranilate synthase activity

“…5f-o) did not induce any significant change in the expression pattern in comparison with previous results with IBA + Kin under comparable conditions [7, 8]. In tobacco TCLs [11], Kin had been supposed to act synergistically with IBA to induce the mitotic activity necessary for callus formation and meristemoid growth, and for this reason it had been then used for arabidopsis TCL culture [10]. By contrast, present results show that Kin is not necessary to arabidopsis TCLs, because the AR meristemoids are formed with IBA alone.…”

“…In Arabidopsis thaliana dark-grown seedlings, IAA is the endogenous inducer of AR formation from the hypocotyl, with biosynthesis, signalling, and transport involved [7–9], however the exogenous application of IBA (10 μM), combined or not with a cytokinin [kinetin (Kin)], improves AR formation [7, 9]. It has been demonstrated a long time ago that IBA applied at 10 μM in combination with 0.1 μM Kin induces AR formation in tobacco and arabidopsis thin cell layers (TCLs) [10, 11]. By contrast, the role of IBA alone in inducing AR formation has not yet demonstrated in this culture system.…”

Simple and Rapid Regeneration of Shoot and Root from Micro-Callus Cultures in Nicotiana tabacum L.

“…Although IBA-induced root formation of tobacco has been reported in the cultures of thin cell layers (Trap Than Van et al, 1974;Torrigiani et al, 1989;Altamura et al, 1991), and leaf explants (Attfield and Evans, 1991), the present study suggests that NAA was more effective for root formation from callus cultures than IBA.…”

Distribution Pattern of Cell Division Centers on the Epidermis of Stem Segments of Torenia fournieri during de Novo Bud Formation

“…Since these first results, others obtained in our research group show that it is possible to control the type of organogenesis from thin layers of epidermal and subepidermal cells (10,18,19,21,22) and to demonstrate organogenetic potentialities in excised parenchymatous subepidermal layers normally masked by intertissue correlations existing in organ fragments (5).…”