Light stimulation of cold acclimation: production of a translocatable promoter.

The light stimulation of cold acclimation of Hedera helix L. var. Thorndale has been shown to result in the production of translocatable promoters of hardiness. Movement of the promoters from an illuminated donor portion to a darkened receptor portion was demonstrated. The majority of transport was acropetal through the phloem and to a much lesser degree basipetal through the xylem. In the early stages of hardening, transport was strictly acropetal. It is suggested that acropetal transport is under the influence of a mobilizing center located in the apex of the plant. Mobilization of the promoters of hardiness was induced by applications of (6)N-benzyladenine. Attempts to characterize the light-generated promoters through fixation of (14)CO(2) and subsequent translocation of (14)C-labeled compounds from the illuminated donor to the darkened receptor indicated that the translocatable promoting material was either some component of the Dowex 1 fraction or sucrose. Furthermore, the hardiness of leaves was significantly increased by sucrose solutions but not by equi-molar solutions of glucose, galactose or mannitol.