Genetic polymorphism of gluten proteins and its utilization for wheat quality improvement

Technological properties of doughs, associated with different bread and durum wheat cultivars, are due to gluten proteins, their composition and their interactions with other seed components, like soluble proteins and starch. Gluten proteins are mainly composed of two protein fractions, termed gliadins and glutenins. The k t group includes monomeric proteins in which disulfide bonds, if present, are intramolecular, whereas the glutenins are large polymenc proteins whose constituent subunits are linked through .intermolecular disulfide bonds. Viscoelastic properties of both durum and bread wheat doughs are positively correlated with the molecular sue of glutenin polymers, that is highly variable and can reach millions of daltons. The size of glutenin polymers depends on the capability of the constituent subunits to form intermolecular disulfide bonds that give rise to polymenc chains of different lengths. Number and position of cysteine residues present in glutenin subunits are one of the major structural features determuiing dough rheological properties. Glutenin subunits are classified into high (HMW-GS) and low (LMW-GS) molecular weight. Electrophoretic studies have shown a high polymorphism for both types of subunits that are correlated with dough qualitative characteristics. Current state of the art of studies on gluten protein composition and its manipulation will be descnbed with the fina1 objective to gain information on the molecular basis of gluten functionality and develop nove1 strategies for quality &iprovement.