EFFECT OF ETHYLENE ON ADVENTITIOUS ROOT-FORMATION AND NICOTINE CONTENT OF TOBACCO CALLUS TISSUES

We studied the influence of ethylene and medium composition on adventi tious root formation and nicotine synthesis in the callus tissue induc ed from the tobacco Nicotiana tabacum cv. Taiyen 5. When ethylene was supplied externally at 10 ppm, adventitious root formation and nicotin e synthesis were inhibited. Depletion of ethylene by adding an ethylen e absorbent caused a remarkable increase in root formation and nicotin e content of calli cultured on Murashige and Skoog medium containing 0 .15 ppm alpha-naphthaleneacetic acid (NAA). When the NAA level was inc reased to 2 ppm and kinetin was added to 0.2 ppm, with the addition of an inhibitor of ethylene action (AgNO3, 10 mu M) or ethylene synthesi s (aminoethoxyvinylglycine, 20 mu M), or an ethylene absorbent, the ca lli formed more adventitious root than did the control, but no signifi cant difference in nicotine accumulation was found. These results show that auxins and cytokinins play roles different from that of ethylene in nicotine synthesis, and that root formation is not an obligatory p rerequisite for nicotine production in the callus tissue. The influenc e of different explant sources on the characteristics of induced calli and the potential role of ethylene in the nicotine synthesis are disc ussed.