Leaf senescence in a non-yellowing cultivar of chrysanthemum (Dendranthemagrandiflora)

Chlorophyll (Chl) and total soluble protein decreased and proteolytic activ ity increased over a It-day period during dark-induced senescence in detach ed leaves of Tara, a yellowing cultivar (Y) of Dendranthema grandiflora. In Boaldi, a non-yellowing cultivar (NY), Chi and soluble protein remained ne ar initial levels and little change in proteolytic activity was observed. S odium dodecyl sulfate polyacrylamide gel electrophoresis of soluble protein s showed no major differences in banding patterns between the two cultivars at day 0; however, all of the resolved proteins were diminished in Tara by day 12. On the other hand, in NY Boaldi, the intensity of the protein band s did not change over the 12-day period. Attached and detached leaves exhib ited similar senescence patterns for each cultivar, Ethylene (100 mul l(-1) ) accelerated the rate of Chl loss in detached leaves of Tara, but had no e ffect on Boaldi, These observations suggest that Boaldi is a stay-green gen otype, possibly a functional type. The results are discussed in relation to the role of ethylene in chrysanthemum leaf senescence.