10 Biochemical and genetical studies of HMW subunits.

D. LAFIANDRA (1), R. D’Ovidio1, S. Masci (1), C. Mattei1, and B. Margiotta (2). (1) Department of Agrobiology and Agrochemistry, University of Tuscia, Viterbo 01100, Italy; (2) Germplasm Institute, C.N.R., Bari 01100, Italy.

A combination of genetical, biochemical and molecular approaches have been used to gain further information on the way high molecular weight (HMW) glutenin subunits affect dough functional properties. Conformational polymorphism of a wide range of allelic HMW glutenin subunits, present in durum and bread wheat, have been determined using transverse urea gradient electrophoresis. Electrophoretic patterns observed for x- and y-type subunits were different with the latter type of subunits showing a behaviour typical of proteins unfolding in a single, cooperative, two state transition Such analyses have also been extended to mutated HMW glutenin subunits expressed in E. coli, differing in the size of the central repetitive domain. Isogenic lines, differing in the type and number of HMW glutenin subunits have been produced. In particular, lines with a number of subunits ranging from one to six have been produced. Furthermore, isogenic lines possessing subunits differing in the number of cysteine residues have also been generated. The constructs corresponding to naturally occurring and mutated subunits, differing in the size of the repetitive domain, expressed in E. coli, have been used in in vitro re-oxidation experiments. The same genes, under control of the same 1Dx5 gene promoter, have been used to prepare constructs for wheat transformation experiments.