Pretreatment of detached carnation petals (Dianhius caryophyUs cv
White Sim) for 24 hours with 0.1 millmar of the cytokinins N'-benzyladenine
(BA), kinetin, and zeatin blocked the conversion of externally
supplied l-aminocyclopropane-1-carboxylic acid (ACC) to ethylene and
delayed petal senescence by 8 days. The normal enhanced wilting and
increase in endogenous levels of ACC and ethylene production following
exposure of petals to ethylene (16 1d/l for 10 hours), were not observed in
BA-pretreated petals. In carnation foliage leaves pretreated with 0.1 mM
BA, a reduction rather than inhibition of the conversion of exogenous ACC
to ethylene was observed. This indicates that foliage leaves respond to
cytokinins in a different way than petals. A constant 24-hour treatment
with BA (0.1 mM) was not able to reduce ethylene production of senescing
carnation petals, while 2 mM aminoxyacetic acid, a known inhibitor of
ACC synthesis, or 10 mM propyl gailate, a free radical scavenger, decreased
ethylene production significantly.