Title: Thidiazuron-induced rapid shoot regeneration via embryo-like structure formation from shoot tip-derived callus culture of sugarcane
Abstract: Rapid shoot regeneration system from callus cultures of a sugarcane (Saccharum officinarum L.) cultivar NiF8 was established. Apical meristematic tissues harvested from young sugarcane shoots were cultured on modified Murashige and Skoog medium containing 2 mg l−1 of 2,4-dichlorophenoxyacetic acid for callus induction. The sugarcane callus was then transferred onto media with different concentrations of thidiazuron (TDZ) (0.5, 1, 2 and 3 mg l−1) with or without 0.1 mg l−1 of 1-naphthaleneacetic acid (NAA) for shoot regeneration. The highest regeneration frequency (80.0%) was observed after three weeks of culture on medium containing 1 mg l−1 TDZ and 0.1 mg l−1 NAA. Histological observation showed that differentiation of proembryoid-like structure with pro-vascular strands were observed 3 days after transfer onto the optimum medium followed by formation of apical meristematic tissue and leaf-like structures after 5 to 7 days, suggesting that TDZ induced rapid shoot regeneration via a process similar to somatic embryogenesis. This study demonstrated a rapid, reproducible and efficient regeneration procedure of sugarcane, which is suitable for biotechnological application including genetic transformation.