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ARS Home » Plains Area » Lincoln, Nebraska » Wheat, Sorghum and Forage Research » Research » Research Project #438954

Research Project: Enriching and Understanding the Wheat Genome by Inducing Secondary Homoeologous Recombination

Location: Wheat, Sorghum and Forage Research

Project Number: 3042-21000-033-027-I
Project Type: Interagency Reimbursable Agreement

Start Date: Aug 15, 2021
End Date: Aug 14, 2024

Objective:
We have produced a large set of wheat germplasm materials (n>1,000) by introducing the genes from goatgrass (Aegilops speltoides, genome SS) and tall wheatgrass (Thinopyrum elongatum, genome EE) into wheat through the genomics-enabled chromosome engineering. In addition, these wheat materials are invaluable genetic resources for genome studies in wheat and its relatives. Many of the wild grass-derived wheat germplasm materials contain the favorable genes useful in wheat breeding (e.g. resistance/tolerance genes for wheat diseases and environmental stresses). However, some of the wheat materials contain the undesired grass genes we do not want, such as late maturity, tall stature, and undesired end-use quality, in addition to the favorable genes. The wild grass-derived undesirable genes need to be removed from the wheat materials to improve their utilities in wheat breeding by chromosome engineering. This chromosome engineering-based alien gene introgression will enrich the genetic composition of the wheat genome and expand its genetic variability. Meanwhile, this work will lead to the development of invaluable genetic resources useful in the genome studies of wheat and its relatives. Following are the specific objectives of this research project: Objective 1. Enhance B-S and B-E recombination toward proximal chromosomal regions and reduce alien segments in the favorable recombinants. Objective 2. Construct composite bin maps of wheat B-genome chromosomes at a relatively high resolution. Objective 3. Remove the ph1b mutant allele from the B-S and B-E recombinants and develop homozygous lines for germplasm development and genome studies. Objective 4. Evaluate the B-S and B-E recombinant lines for the traits of interest and develop breeding-ready germplasm in the adapted wheat backgrounds.

Approach:
Following are the approaches used to accomplish each of the objectives: Objective 1. Enhance B-S and B-E recombination toward proximal chromosomal regions and reduce alien segments in the favorable recombinants We will produce wheat materials that contain the genes of interest on the reduced wild grass chromosome segments without deleterious genes under this objective. The wild grass-derived genes targeted in this project include those for resistance to the rust, tan spot, Stagonospora nodorum blotch (SNB), and Fusarium head blight diseases and for tolerance to salt and waterlogging. We anticipate developing breeder-friendly wheat germplasm containing the wild grass-derived resistance/tolerance genes for the development of superior varieties. This will make the wild grass genes usable in wheat breeding and strengthen the defense of the U.S. wheats against the diseases and environmental stresses. Objective 2. Construct composite bin maps of wheat B-genome chromosomes at a relatively high resolution. The wheat materials developed under Objective 1 dissect the large and complex genome of wheat and are extremely useful in wheat genome studies. We will use those materials to partition the wheat genome and position the genes and other DNA sequences in the wheat genome. This will lead to the construction of a unique framework for the genome studies in wheat and its relatives. Objective 3. Remove the ph1b mutant allele from the B-S and B-E recombinants and develop homozygous recombinant lines for germplasm development and genome studies. The mutant gene (i.e. ph1b mutant) used for chromosome engineering in this study will be removed from the germplasm materials because it causes genetic instability. The genetically-stable wheat germplasm homozygous for the wild grass-derived genes of interest will be developed under this objective. This will make the wheat germplasm materials ready for variety development in wheat breeding. Objective 4. Evaluate the B-S and B-E recombinant lines for the traits of interest and develop breeding-ready germplasm in the adapted wheat backgrounds. We will evaluate the wheat germplasm materials for the traits targeted in this study and select the germplasm that contain the gene of interest, but no deleterious genes. Meanwhile, we will incorporate the wild grass-derived favorable genes into the adapted wheat genotypes to develop elite germplasm lines for variety development in wheat breeding.