Hairy roots cultures from different Solanaceous species have varying capacities to produce E. coli B-subunit heat-labile toxin antigen

The gene encoding enterotoxigenic Escherichia coli B-subunit heat-labile toxin (LTB) antigen was co-transformed into hairy root cultures of Nicotiana tabacum (tobacco), Solanum lycopersicum (tomato) and Petunia parodii (petunia) under the CaMV35S promoter. Tobacco and petunia roots contained similar to 65-70 mu g LTB g(-1) tissue whilst hairy roots of tomato contained similar to 10 mu g LTB g(-1). Antigen at similar to 600 ng ml(-1) was detected in growth medium of tobacco and petunia. Tobacco roots with higher LTB levels showed growth retardation of similar to 80 whereas petunia hairy roots with similar levels of LTB showed only similar to 35 growth retardation, relative to vector controls. Regeneration of plants from LTB-containing tobacco hairy roots was readily achieved and re-initiated hairy roots from greenhouse-grown plants showed similar growth and LTB production characteristics as the original hairy root cultures.