Rapid Oscillations in Fructose 2,6-Bisphosphate Levels in Plant Tissues

The fructose 2,6-bisphosphate (Fru 2,6-P(2)) content of pea, Pisum sativum, roots and leaves were measured following flooding with water and found to change in times of minutes and to exhibit oscillatory-type changes. Each organ changes its Fru 2,6-P(2) content in a unique pattern in response to environmental disturbances such as flooding or light. For example, when roots of intact illuminated pea plants are flooded, roots decrease their Fru 2,6-P(2) content while simultaneously leaves increase their Fru 2,6-P(2) content; but both organs exhibit oscillatory-type patterns within flooding time of about 30 minutes. Half-change times can be as rapid as 2 to 3 minutes. The endogenous extractable activity of the root pyrophosphate-dependent phosphofructokinase also exhibits an oscillatory pattern upon root immersion slightly after Fru 2,6-P(2) changes occur. We postulate from these results that Fru 2,6-P(2) is a primary signal molecule which enables plants to regulate their metabolism to cope with changing environments.