INVOLVEMENT OF ETHYLENE ON GROWTH AND PLANT-REGENERATION IN CALLUS-CULTURES OF HELICONIA-PSITTACORUM L F

The level of ethylene accumulated in morphogenic callus cultures of He liconia psittacorum L.f. was only one quarter that of non-morphogenic cultures. The rate of ethylene production in the morphogenic callus cu ltures during early stages of differentiation of protocorm-like bodies leading to plantlet regeneration was 10-fold higher than that during callus proliferation. In cultures sealed with gastight serum caps, fre sh weight gain was reduced 2- to 3-fold compared to those that were cl osed with Kaputs(R). Treatment with 1-aminocyclopropane-1-carboxylic a cid (greater than or equal to 100 mu M) caused complete inhibition of plant regeneration from the morphogenic callus on subsequent culture u nder inductive conditions. Silver nitrate and aminoethoxyvinylglycine also reduced plant regeneration. These results indicate that while hig h levels of ethylene were inhibitory, a low level of endogenous ethyle ne production may be necessary during the plant regeneration phase in callus cultures of Heliconia.