Influence of the Antibiotic Ciprofloxacin on Culture of Allium longicuspis Callus-derived Protoplasts

A major problem of in vitro plant culture techniques is chronic contamination by microorganisms. Calli derived from basal parts of leaves of Allium longicuspis Regel (Alliaceae) and cultured in a medium without antibiotic contain most probably latent contaminating microorganisms. These calli were used as the source material for isolation and culture of protoplasts. Isolated protoplasts were cultured in the presence of the antibiotic ciprofloxacin, and the protoplast viability, cell wall regeneration and cell division were studied as a function of the antibiotic concentration. Whatever the antibiotic concentration, protoplast-derived cells kept significantly higher viability for at least 3 weeks compared with those cultured without antibiotic. As to cell wall regeneration after 2 d, it was not affected by the antibiotic except at the highest concentration tested (100 mg l -1). Sporadic first cell division was observed after 2-6 d of culture in the presence of ciprofloxacin while, in its absence, cell division was never apparent before 10 d of culture.