Development of a highly efficient callus induction and plant regeneration system for Dendrocalamus sinicus using hypocotyls as explants

Dendrocalamus sinicus is the largest bamboo species in the world. To aid its rapid propagation and explore its desired traits, we identified the optimal medium and culture conditions for callus induction, shoot differentiation, rooting and transplanting using hypocotyls as explants. Comparison of three browning inhibitors indicated that 400 mg/L of citric acid provided the best results. The Box-Behnken model showed that 6-benzyladenine (6-BA), citric acid and 2,4-dichlorophenoxyacetic acid (2,4-D) had decreasing levels of impact on the callus induction rate of D. sinicus, with their optimum concentrations being 2.10 mg/L, 420 mg/L and 3.10 mg/L, respectively. Under these conditions, the callus induction rate of D. sinicus hypocotyls was predicted to be as high as 89.06%, and was validated as 88.87% in our experiments. The highest frequency of callus formation was on Murashige and Skoog (MS) medium containing 30 g/L sucrose, 6 g/L agar, 500 mg/L casein hydrolysate (CH), 500 mg/L proline (Pro), 500 mg/L glutamine (Gln), 2.10 mg/L 6-BA, 420 mg/L citric acid and 3.10 mg/L 2,4-D. After further callus differentiation, rooting and regeneration, the rooting rate and survival rate of transplanted seedlings reached 91% and 93%, respectively. Our study provides a theoretical basis and a new avenue for the genetic transformation of bamboo plants. The main objective of this study was to construct a highly efficient callus induction and plant regeneration system for the largest bamboo species in the world by hypocotyls as explants based on response surface method.