Sucrose metabolism during the growth of Camellia japonica pollen

Abstract

The free sugar in the mature pollen grains of Camellia japonica is almost all sucrose and the sucrose content decreases rapidly during pollen growth. The activity of soluble invertase increases during culturing and a high constant activity was found at the later stages of pollen tube growth. By contrast, the level of sucrose synthetase activity remains constant during pollen growth and that of wall-bound invertase activity is very low. Cycloheximide has little effect on the activity of these enzymes. Exogenous sucrose or glucose was simultaneously incorporated into the pollen grains when they absorbed water and swelled. The free sugar levels in growing pollen depend on the nature of the exogenous sugar. The sugar metabolism in the pollen at the stage of germination differs from that during tube growth, the latter being particularly influenced by exogenous sugar.