Granulebound starch synthase (GBSS), also called waxy protein, is the key enzyme for amylose synthesis in the endosperm of cereals and is encoded by the waxy genes.

Both drought and waterlogging resulted in decreases in the activities of sucrose synthase (SS) and granule-bound starch synthase (GBSS), and especially in that of soluble starch synthase (SSS).

The progress in research granule-bound starch synthase (GBSS) which was responsible for amylose synthesis in cereal endosperm, was reviewed in the paper.