2011 Annual Report
1a.Objectives (from AD-416)
Determine the genetic basis of wheat end-use properties, specifically the structural attributes of high-molecular-weight glutenins that determine dough strength, the effects of over-expression of gliadins with extra cysteine residues on polymer formation, the types of low-molecular-weight glutenins and gliadins that form the largest and strongest gluten polymers, and the molecular and physiological basis for the increase in grain protein content associated with the presence of a gene introgressed from wild durum wheat. Develop transgenic wheats with high gluten strength whose only non-wheat DNA is a short non-protein-encoding sequence for site-specific recombination.
1b.Approach (from AD-416)
Use molecular biology to make coding regions for expression of variant gluten proteins in wheat. Use genetic transformation to introduce genes encoding variant and natural gluten proteins into wheat. Characterize transgene inheritance using genetics and transgene expression levels using molecular biology, biochemistry, and cereal chemistry. Determine dough mixing properties and gluten polymer characteristics in flours with transgene-encoded gluten proteins. Collaborate to test transgenes for their effects on wheat grain protein content and agronomic traits in field trials. Replacing 5325-21430-011-00D (June/2010).
Research continued with the goal of understanding the roles played by wheat seed proteins in the functionality of wheat flours. True-breeding lines were derived from transgenic wheat plants that contain genes designed to test the gluten polymer-building roles of two cysteine amino acids in a glutenin protein that is associated with strong and elastic bread doughs. A collaboration with other ARS researchers showed that the strong-dough characteristics of transgenic wheat lines produced in previous years of the project could be transferred to hard red winter Midwest wheat varieties by genetic crosses. In FY11, the project also showed that the Bxb site-specific recombinase was active in transgenic wheat leaves and can excise DNA from reporter genes that contain its recognition sequences. Collaborative research produced transgenic wheat plants containing 5 different constructions designed to understand and improve wheat’s resistance to the stripe rust fungal pathogen. The disease resistance of these plants is currently being evaluated. The knowledge obtained in this research is enabling biotechnologists and breeders to improve wheat end-use properties and disease resistance more efficiently.
Graybosch, R.A., Seabourn, B.W., Chen, Y.R., Blechl, A.E. 2010. Quality and agronomic effects of three high-molecular-weight glutenin subunit transgenic events in winter wheat. Cereal Chemistry. 88(1):95-102.