Location: Crop Improvement and Genetics Research2013 Annual Report
1a. Objectives (from AD-416):
The long-term goal of this project is to understand and control the genetic and molecular basis of wheat quality traits conferred both by the seed proteins and other factors contributing to seed formation (directly or indirectly through plant fitness). Objective 1: Generate novel genetic and genomic sequence information and resources for wheat breeding. • Sub-objective 1.A. – Mapping of the wheat D-genome. • Sub-objective 1.B. – Sequencing of the wheat 3D chromosome. • Sub-objective 1.C. – Completion of the sequencing of the complete set of wheat prolamin loci. Objective 2: Characterize genes and mechanisms for important wheat traits such as baking quality and cold temperature tolerance. • Sub-objective 2.A. – Molecular dissection of wheat HMW-subunit contributions to baking quality. • Sub-objective 2.B. – Application of molecular, genomic, and bioinformatic tools to developmental and metabolic traits.
1b. Approach (from AD-416):
Objective 1: Generate novel genetic and genomic sequence information and resources for wheat breeding. • Sub-objective 1.A. - Map the wheat D-genome using radiation hybrid wheat lines, constructing a linkage map of the D-genome, and constructing a physical map of the wheat genome through a minimum-tiling-path (MTP) of bacterial-artificial-chromosomes (BACs). Integration of all such maps once mapping is complete. • Sub-objective 1.B. – Sequence the MTP of the wheat 3D chromosome using Roche 454 technology. The chromosome sequence will be annotated along with collaborators and made available to public databases. • Sub-objective 1.C. – Sequence with Roche 454 technology and analyze wheat contiguous genomics regions spanning the prolamin loci responsible for wheat quality characteristics to further understanding of the evolution, expression, and regulation of prolamin genes in wheat. Objective 2: Characterize genes and mechanisms for wheat traits focusing on two important traits; i.e., baking quality and cold temperature tolerance. • Sub-objective 2.A. – Molecular dissection of wheat HMW-subunit contributions to baking quality. The three approaches under this sub-objective involve alterations in seed prolamin structure, alteration in total seed prolamin composition, and studying mechanisms for processing of wheat prolamins during seed development. Experimental approaches will include laboratory studies of modified prolamins and mutagenized wheat lines with altered prolamin compositions and the effects on dough properties. Prolamin sub-cellular processing will be studied using modified prolamins with specific molecular tags. • Sub-objective 2.B. – The application of molecular and genomic tools to cold temperature tolerance. The specific goal is to identify the genetic factors critical to the development of wheat cold temperature tolerance. The approach will utilize genetic stocks, double haploid mapping populations, and genotype-by-sequencing to identify genes involved in cold-temperature tolerance. The objectives will be accomplished with the following approaches: 1) Integrate genetic, physical, and radiation hybrid maps of Ae. tauschii to provide a foundational framework for sequencing the wheat D genome. 2) Contribute to a collaboration to sequence the minimum tiling path (MTP) of the Ae. tauschii 3D chromosome. 3) Sequence and analyze contiguous genomics regions spanning the prolamin loci of wheat. 4) Study the structure, composition, and processing of seed prolamin correlate changes in structure and composition with wheat quality characteristics. 5) Map and characterize genes involved in cold tolerance by testing for correlations with cold temperature tolerance phenotype in wheat.
3. Progress Report:
This is the first report for this new project which continues research from 5325-21000-015-00D, "Genomics and Molecular Approaches to Wheat Traits", which terminated on 5/12/2013 and was replaced with this new project. Important discoveries were achieved under 5325-21000-015-00D, including the following: The draft of the genome for bread wheat was completed and published as an original research article in Nature; An integrated genetic and physical map for wheat (D genome) was developed; genomic markers (RJMs and SNPs) were developed to accelerate wheat germplasm improvement by marker assisted selection; New classes/members of gliadin genes and proteins were characterized; bread wheat lines deficient in specific seed storage proteins were generated as an initial step to develop healthier wheat varieties; Genes critical for the development of cold tolerance in wheat were identified. Significant results were also accomplished in our collaborative effort to develop and utilize Brachypodium as a model system for Triticeae research for grain quality and other traits: The draft of the Brachypodium genome was completed and was also published in Nature; Results from the deep sequencing of genes expressed in Brachypodium were released to the public; T-DNA tagged lines of Brachypodium were generated and distributed to the public; and the major seed storage protein in Brachypodium was identified.