CALIFORNIA
USDA-ARS WESTERN REGIONAL RESEARCH CENTER
Wheat Biotechnology and Wheat Genetic Engineering Groups, 800 Buchanan St., Albany, CA 94710, USA.
Michael Gitt.
Our laboratory's interests have expanded, along with the number
of personnel. Although still maintaining our work in elucidating
the mechanisms of dough viscoelasticity, we also are part of a
large intramural project seeking to markedly expand the genomic
database of expressed sequences in wheat under varying conditions
and in various tissues.
The director of these projects is Olin D. Anderson. Personnel involved in the projects are Gerry Lazo, Vickie Carollo, Michael Gitt, Shiaoman Chao, Cheryl Hsia, Phyllis Han, Carrie Rausch, Ruthellen Miller, Yurah Kang, Cheryl Seaton, Jason Chang, Jenny Tong, Debbie Laudencia Chincuango, and Ed Butler.
Because the genome of hexaploid bread wheat is magnitudes larger than the human genome, we have began the genomics study with the expressed portion of the genome first. Several cDNA libraries from different tissues and from the same tissue under different conditions have been prepared and are now in the process of high-throughput sequencing using PE Applied Biosystems ABI 3700 and Beckmann CEQ2000 sequencers. This large quantity of sequences is then processed to a usable form by software being refined in the laboratory and will appear in the GrainGenes database.
The laboratory maintains the GrainGenes database (http://wheat.pw.usda.gov), which permits web-based homology searches to wheat, oat, barley, rice, sugarcane, maize, and noncereals.
We are continuing service to the cereal research community by banking and partially characterizing all clones that we and others provide. We also make these clones available for the entire research community. This past year, we distributed over 1,500 individual clones from the probe repository. Clones can be ordered by contacting probes@pw.usda.gov.
We are pursuing several strategies for increasing the amount of lysine in wheat seed proteins, with the aim of increasing the nutritive value of this major source of dietary protein both for humans and farm animals for whom lysine is an essential amino acid. Preliminary tests will assess effects of the changes on dough properties.
We have engineered a synthetic version of the high molecular weight glutenin, Dx5, which is highly expressed in E. coli. We also have generated several mutations in this gene, targeting amino acids that are hypothesized to play a central role in intermolecular interactions in the gluten polymer. After expressing these mutants in a bacterial expression system, we can study their effect on mixing parameters of dough and thereby learn about interactions responsible for dough viscoelasticity.
We have sequenced upstream and downstream regions of the genes encoding Ax, Ay, Bx, By, Dx, and Dy HMW glutenins. These flanking sequences provide information on the evolution of the various glutenin alleles and suggest new control sequences that could prove useful in future transgenic work. We also have isolated several gliadin genes and have discovered new classes of gliadins.