Heat shock pre-treatment enhances the response of Arabidopsis thaliana leaves and Cucurbita pepo cotyledons to benzyladenine

The effects of heat shock (HS) pre-treatment on the response to benzyladeni ne were studied in two plant model systems (1) retardation of senescence of Arabidopsis thaliana L. Heyhn rosette leaves and (2) induction of greening of detached Cucurbita pepo L. cotyledons. N-6-benzyladenine (BA) retarded senescence of rosette leaves of Arabidopsis thaliana (L) Heyhn and brief pr e-treatment with HS (3 at 37 degreesC) essentially enhanced this cytokinin effect. BA stimulated cotyledon greening in Cucurbita pepo L due to the act ivation of chlorophyll synthesis. Brief cotyledon pre-heating at moderate t emperatures (3 at 33-35 degreesC) also enhanced this cytokinin effect.