Response of fructose-2,6-bisphosphate to environmental changes. Effect of low temperature in winter and spring wheat - Three day old, etiolated, wheat seedlings were affected differently according to the duration of exposure to a non-freezing low temperature (5°C). Indeed, growth was only reduced after a 45 min or longer treatment. Germs exposed to a 120 min cold period were half the size 24 h after the cold treatment; in comparison to the room temperature (20°C) exposed seedlings. ln respect with these previous results, the content of Fru-2,6-P2 was further analyzed in wheat germs. A ten min cold exposure did not induce any obvious modifications. A longer treatment ( 120 min, soC) induced important fluctuations in the concentration of Fru-2,6-P2. These were significantly larger than those observed in the control treatment. Such fluctuations were present in two winter wheat varieties (Fidel, Vienna) and, to a lesser extent, in one spring variety (Frisai). The present work shows the high dynamic capacity of changes of the regulatory sugar Fru-2.6-P2 in plants with respect to temperature changes