Effects of non-frozen cold storage on the growth,organogenesis and secondary metabolism of callus cultures

Callus tissues derived from chilling-tolerant herbaceous plant, Atractylodes lancea, Atropa belladonna, Bupleurum falcatum, Dioscorea tokoro, Lithospermum erythrorhizon and Phytolacca americana could be cold-stored at 4°C for three months or more, whereas those from chilling-sensitive herbaceous plants such as Datura innoxia and Perilla frutescens var. crispa and a deciduous tree, Mallotus japonicus, could not survive after cold storage for two to three months. Tobacco callus cultures could be stored at 4°C for two or four months depending on a callus strain. The effect of cold storage on secondary metabolite production varied. Nicotine and betalain production suffered from cold storage of tobacco and Phytolacca americana callus cultures, respectively. However, production of anthocyanin in cultures of Mallotus japonicus and Bupleurum falcatum and shikonin derivatives in Lithospermum erythrorhizon callus was affected very little. Root-forming ability was retained for more than one year in cold-stored callus tissues of Bupleurum falcatum, while the control callus tissues maintained at 25°C completely lost the organogenetic ability six months after the first subculture.