Starch, accounts for 65-75% of wheat grain dry weight and it is composed of two different glucan chains, amylose and amylopectin. Enzymes involved in starch synthesis and, particularly, the role of five isoforms of starch synthases (SS) have been identified. Four of these are involved in amylopectin synthesis, along with branching and debranching enzymes; whereas the granule bound starch synthases (GBSSI or waxy proteins) are responsible for amylose synthesis in storage tissues. Electrophoretic analyses of common and durum wheat have led to the identification of partial waxy mutant lines, characterised by the lack of one or two waxy proteins. Crossing of these materials has permitted the combination of the different null alleles detected to produce the entire set of partial and complete waxy lines. Similarly, a different set of mutant lines (SSIIa nulls) has been used to produce durum and bread wheat varying in number of SGP-1 proteins.