THIDIAZURON AND PACLOBUTRAZOL APPEAR TO MIMIC CYTOKININ AND AUXIN INFLUENCES ON ORGAN REGENERATION AND PROTEIN PROFILES IN CULTURED MELON COTYLEDONS

The bioregulators thidiazuron (TDZ) and paclobutrazol (PC) appear to m imic the effects of cytokinin and auxin, respectively, on organogenesi s and on the temporal changes of the reserve polypeptide, P20-25, in c ultured melon cotyledons. TDZ exerts its cytokinin-like influence by s hoot induction and inhibition of root initiation. The plant growth ret ardant PC is a potent root-inducer and it overcomes the inhibitory eff ect of exogenous 10(-5)M BA.P. The typical stunted shape of PC-induced roots made it possible to determine that PC induced rooting irreversi bly on the first day of culture. PC induced roots only at the basal cu t of the cotyledon and was not able to do so when TIBA was incorporate d in the growth medium.