The effects of antibiotics and their breakdown products on the in vitro growth of Antirrhinum majus

Summary The effects of various antibiotics on the development of hypocotyls of Antirrhinum majus in tissue culture have been studied. The penicillins, carbenicillin and penicillin G, have been shown to stimulate callus growth, have little impact on shoot production and may stimulate root formation. The cephalosporins, cephotaxime and cephalosporin, have no effect on callus production and reduce shoot and root formation. HPLC, GC and GC-MS analyses have shown that concentrations of carbenicillin and penicillin G, commonly used in plant tissue culture, break down to give physiologically active levels of the auxin phenylacetic acid. This offers a mechanism for the stimulation of growth caused by these two antibiotics.Abbreviations Amp ampicillin - 6APA 6 aminopenicillanic acid - BAP benzyl amino purine - Cb carbenicillin - Cb_n and Cb_o 1 month and 1 year old samples respectively of carbenicillin stored at 4°C as powder - Cph cephalothin - Cx cephotaxime - IAA indoleacetic acid - MS Murashige and Skoog medium - NOA -naphthoxyacetic acid - PAA phenylacetic acid - PenG benzyl penicillin - PMA phenylmalonic acid