COMPARATIVE STARCH SYNTHASE ACTIVITY OF INDICA AND JAPONICA DEVELOPING RICE GRAIN

Developing grain of japonica rice had higher specific activity of granule-bound starch synthase than indica rice at the same growth stage, with indica-japonica hybrid having intermediate synthase activity. All were of similar amylose content in the mature grain. It supports an earlier speculation that for japonica rice to synthesize the same amount of amylose in its starch granule with a lower level of bound starch synthase, it must have a more efficient enzyme than indica.