The Effect of Sucrose on Sucrose Synthase Activity in Rice Grains during Filling Period

Sucrose synthase is an important enzyme for sucrose metabolism of plants.In vitro ear culture was used to determine the regulatory effect of sucrose on sucrose synthase activity.The results indicated that sucrose synthase activity was improved remarkably in rice grains by treatment with sucrose,and promoted with increase of sucrose concentration.If sucrose was replaced by the same concen-tration of osmotica regulators,monosaccharide or its mixtures,such as mannite,sorbierite,potassium chloride,glucose and fructose,the same effect didn't appear.It shows that the effect of sucrose on sucrose synthase activity is not due to osmotic stress.