Establishment of a Callus-Based Regeneration System for Lilium regale

Abstract

Induction of callus is an important step to produce high-quality seedlings, to promote the large-scale production of seedings, and to establish stable transgenic methods. To establish an efficient callus-based regeneration system for lily, in this study, we used the scales of Lilium regale as explants and employed plant tissue thin-layer culture to induce callus tissues. To examine the effects of different types and concentrations of plant growth regulators (PGRs) on the induction of lily callus tissues and plant regeneration, we designed orthogonal experiments using three PGRs: 6-BA, NAA, and PIC, with each regulator at three concentration levels. The results indicated that a suitable medium for inducing callus under the experimental conditions was 1.00 mg/L 6-BA + 0.05 mg/L NAA + 2.00 mg/L PIC, pH = 5.8 because in this medium, callus tissue showed a good balance of induction and contamination rate, as well as very low redifferentiation into bulbs. Under the experimental conditions, a suitable medium for callus expansion was 1 mg/L 6-BA + 0.5 mg/L NAA, pH = 5.8. We also showed that the induced callus tissues could develop into seedlings. These findings provide important references for optimizing in vitro culture systems of Lilium regale and offer supports for tissue culture studies of other lily species.