The effect of photoperiod on flower formation in vitro in a quantitative short‐day cultivar of Nicotiana tabacum

Publisher Website
Google Scholar
Abstract
Superficial 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.