In vitro direct organogenesis in response to floral reversion in lily

Abstract

Our previous study indicated that the tiger lily (Lilium lancifolium var. Flore Pleno) has a great ability to produce inflorescence bulbils in nature as a form of natural phenomenon of floral reversion in plants. This present research was carried out to investigate the artificial floral reversion in in vitro culture of two lilies (Asiatic hybrid cv.”Black out"), and (Lilium longiflorum cv "White heaven") based on the type and developmental stage of explants plus the different concentrations of naphthalene acetic acid (NAA) and benzyl aminopurine (BA). Developmental changes were observed in both lilies in response to floral reversion which was enhanced by growth regulators under in vitro condition. The regeneration of vegetative organs was associated with certain degeneration of floral organs. Large bulblets and multiple shoots were formed only in specific regions in floral organs, precisely in two attached points: the boundary region between the receptacle with other floral organs and the branching point where the peduncle joins the pedicel. This direct organogenesis was highly dependent on type of lily, type and developmental stage of explants in addition to the concentration of BA and NAA in in vitro culture. However, 1 mg/L BA combined with 0.1 mg/L NAA was the optimum for regenerating shoots and bulblets in in vitro culture of both lilies after six weeks.

Key words: Floral reversion, organogenesis, lilies, active points, growth regulators, in vitro, bulblets.