Tissue culture of endod (Phytolacca dodecandra L'Herit) : growth and production of ribosome-inactivating proteins

Leaves and stems from endod (Phytolacca dodecandra L'Herit), known to produce the 29 kDa ribosome-inactivating protein (RIP) dodecandrin, were initiated into tissue culture. Callus and suspension cultures were maintained on modified Murashige and Skoog medium plus 1.0 mg/l 2,4-dichlorophenoxyacetic acid. Six callus and two suspension cell lines were screened for dodecandrin production by western blots with affinitypurified antiserum. Antiribosomal activity of culture extracts was tested by in vitro translation assays. One suspension cell line was found to be free of immunoreactive proteins and a ribosome inhibitor. All other cell lines contain a ribosome inhibitor, although only two callus cell lines show detectable amounts of immunoreactive proteins at the same Mr as dodecandrin. Other immuno-reactive proteins were detected in callus (Mr 31000, 33000, 41000 and 43000) and in suspension cells (Mr 23000 and ∼43000), and may be ribosome inhibitors related to dodecandrin-either other RIPs or dodecandrin at various stages of processing.