11 Manipulation of HMW subunit composition and its impact on processing properties.

P. R. SHEWRY. IACR-Long Ashton Research Station, Department of Agricultural Sciences, University of Bristol, Long Ashton, Bristol BS41 9AF, UK.

Transgenic wheat is being used to explore the relationship between grain functional properties and the amount, composition and characteristics of the HMW subunits, in collaboration with IACR-Rothamsted, the University of Tuscia, INRA Nantes and CSIRO North Ryde. Two near isogenic lines expressing either two (1Bx17 + 1By18) or five (1Ax1, 1Dx5 + 1DY10, 1Bx17 + 1By18) HMW subunits have been transformed with constructs encoding long and short forms of subunit 1Dx5, subunit 1Dx2.2* and a 1Ay subunit from a diploid wheat. Transformants showing altered HMW subunit composition are being selected and multiplied. Similar lines, expressing wild type genes for subunits 1Ax1 or 1Dx5, have been grown in the glasshouse and in replicated field trials over two seasons on two sites (IACR-Long Ashton and IACR-Rothamsted). This has provided information on yield and performance and allowed detailed studies to be made of their rheological and mixing properties. The results demonstrate that transformation can be used to develop varieties with improved or novel end use properties as well as providing a tool to study structure: functionality relationships in wheat gluten.