Beschreibung:
<jats:p>Chelating agents were applied to petunia flowers to test for the involvement of apoplastic metal ions in ethylene-induced senescence. Compounds varying in polarity and charge were applied directly to the corolla prior to a 24-h treatment with 1 ppm ethylene. Charged and polar chelators were inactive. The only compound that inhibited senescence was 2,2'-dipyridyl, and there was evidence of cellular uptake of this compound. Fe<jats:sup>2+</jats:sup> and Zn<jats:sup>2+</jats:sup> did not reverse the inhibition of senescence by dipyridyl. Cu<jats:sup>2+</jats:sup> as low as 0.1 mM reversed the effect of dipyridyl, but the time of senescence was independent of ethylene treatment. Dipyridyl caused a rapid shift in flower color from red to blue, but untreated flowers became more blue than dipyridyl-treated during 9 days. CO<jats:sub>2</jats:sub> and ethylene production were stimulated by ethylene, but inhibited by dipyridyl applied before or after a 24-h ethylene treatment. Continuous ethylene treatments did not reverse the delay of senescence by dipyridyl.</jats:p>