EFFECTS OF CHILLING AND TEMPERATURE PRECONDITIONING ON THE ACTIVITY OF POLYAMINE BIOSYNTHETIC-ENZYMES IN ZUCCHINI SQUASH

Polyamine bisynthesis during chilling stress in zucchini squash (Cucurbita pepo L., cv. «Ambassador») was measured by detemining the activities of SAMDC, ADC, and ODC. Stree induced increases in Put were correlated with increased ODC activity. Decreases in the levels odf Spd and Spn during chilling may be related to decreased SAMDC activity. Temperature preconditioning adapts squash to subsequent chilling stress and results in increased Spn and Spd levels in response to chilling. The concominant increase in these two polyamines is correlated with elevated SAMDC activity. These data support the view that the mechanism by which temperature preconditioning inhibits chilling injury involves the induction of polyamine biosynthesis. © 1990, Gustav Fischer Verlag, Stuttgart. All rights reserved.