Callus Induction And Plantlet Regeneration In Dendrocalamus Hamiltonii

In this study, using mature zygotic embryos as explants, plant growth regulators and various media were tested with the aim of selecting out the appropriate culture components and culture condition for callus initiation, callus maintenance, shoot differentiation and plantlet rooting of the bamboo species Dendrocalamus hamiltonii. We firstly developed an efficient and consistent regeneration system for plantlets of the bamboo species D. hamiltonii, providing a useful basis for developing culture protocols of the regeneration of bamboo plants and a platform for genetic transformation in bamboo species.The main results obtained are presented as follows:1 Callus formation was induced in explants cultured in Murashige and Skoog (MS) medium supplemented with 3 mg·L^-1 2,4-dichlorophenoxyacetic acid (2,4-D), 500 mg·L^-1 proline (Pro), 500 mg·L^-1 glutamine (Gln), 500 mg·L^-1 casein hydrolysate (CH), with the frequency of callus and granular and compact callus to 80% and 60% respectively.2 Low concentration of kinetin (KT, 0.5 mg·L^-1) did not significantly improve callus growth during subculture. Meanwhile, high concentrations of KT(1or 2 mg·L^-1)had a detrimental effect on callus growth, resulting in callus browning and loss of maintenance and differentiation potential.3 Optimal shoot differentiation and subsequent shoot growth were obtained in MS medium supplemented with 2 mg·L^-1 benzyladenine (BA), 4 mg·L^-1 KT, and 1 mg·L^-1 naphthaleneacetic acid (NAA), 30 g·L^-1 sucrose and 8 g·L^-1 Type A agar, with the highest differentiation rate of 89.5%.4 Root induction was enhanced by the addition of 5 mg·L^-1 indole-3-butyric acid (IBA) to the culture medium. 7-8 roots were induced per shoot in 10 days and the rooting rate was up to 80%. Rooted plantlets were transferred to artificial mixture (peat: vermiculite: perlite=1:1:1) with 100% shoot survival.5 Histological analysis revealed that both somatic embryogenesis and organogenesis were induced during callus differentiation and the development of plantlets from the mature zygotic embryos.6. Transgenic albino plantlets were obtained by Agrobacterium-mediated transformation. Transient GUS expression was observed in resistant calli and regenerated plantlets.