2009 Annual Report
1a.Objectives (from AD-416)
A major goal of wheat improvement is to identify, isolate, and characterize genes and gene complexes that control value-added traits that can be introduced into commercial cultivars to improve production. Historically, once such gene complexes were identified and characterized they were manipulated into a hexaploid wheat background for improved production. Once the options for trait improvement genes in the available wheat germplasm were exhausted wheat geneticists turned to other members of the Triticeae tribe (cereals) as desirable genetic resources for trait exploitation. However, to date only a few gene complexes from non-wheat related species and genera have been characterized, manipulated and introduced into wheat. The lack of advancement in this area results from an undesirable linkage drag, resulting in low yields, that is associated with the transference of gene complexes from related species. This laboratory has developed methods for the efficient transferring of value-added gene complexes, without linkage drag, from rye into wheat for wheat improvement. This project will utilize these previously developed technologies of chromosomal centric-break and fusion translocations to transfer the value added traits of disease resistance and abiotic stress tolerance from rye and wheat-rye hybrids (triticales) to commercially useful hexaploid wheat cultivars. In particular the project will focus on 1. Identifying novel genetic elements associated with resistance to new strains of stem rust linked to rye chromosome 1R within local and world stock collections of triticales and spring ryes for transfer into hexaploid wheat, and 2. Identifying, characterizing and transferring novel genetic elements, regardless of chromosomal location, for resistance to stem and leaf rusts and tolerance to low pH and saline soils for transfer into hexaploid wheat. Objective 1: Develop, evaluate, and distribute wheat-rye aneuploid stocks. Objective 2: Use rye genes and gene complexes to improve stem and leaf rust resistance and abiotic stress tolerance in wheat.
1b.Approach (from AD-416)
To create and characterize wheat containing 1RS/1BL wheat/rye translocations. The present discovery-driven objective was designed to screen all newly developed wheat/rye translocation stocks, from every rye chromosome arm, for resistance to new races of leaf and stem rust, as well as screen for new levels of tolerance to select abiotic stresses.
We have created three new wheat/rye hybrids utilizing newly characterized rye accessions that were found to be resistant to all forms of stem rust including UG99 and initiated the transfer of the critical rye chromosome arms from these accessions into a common wheat background. We have completed the stem rust screening of a rye germplasm collection in collaboration with the USDA-ARS, Cereal Disease Laboratory, University of Minnesota, St. Paul, MN. The screened rye accessions resistant to stem rust have been crossed to hexaploid wheat. The screening of three newly developed triticale hybrids for stem rust resistance has been initiated in collaboration with the USDA-ARS, Cereal Disease Laboratory, University of Minnesota, St. Paul, MN. The stem rust screening in the USDA-ARS, Cereal Disease Laboratory is seasonal due to demands on that facility and so the rye accessions have been sent to East Africa for field testing in the environment where the new UG99 stem rust race was first identified. We continue to maintain and distribute wheat-rye genetic stocks and the USDA-Sears Collection of wheat aneuploids.
New sources of stem rust resistance for wheat. New races of wheat stem rust are rapidly spreading around the world, thus raising the potential for a world rust epidemic, which will devastate the production of wheat, the world’s major food crop. One race in particular, Ug99, is rapidly spreading throughout East Africa and the Middle East and data has shown that most of the wheat cultivars in the world are susceptible to Ug99. The ARS scientist in Columbia, Missouri in collaboration with ARS scientists in Minneapolis, Minnesota identified several accessions of rye that were completely resistant to all known races of wheat stem rust including Ug99. The ARS scientist in Columbia has created several wheat/rye hybrids from stem rust susceptible wheat and the different rye accessions that were identified as stem rust resistant in 2008. The new ARS wheat/rye hybrids constitute a valuable genetic source of stem rust resistance for incorporation into wheat for commercial production. This is very important for wheat production on a world scale and is part of an expanded project to incorporate value-added traits of interest for wheat breeders from rye without involving the techniques associated with the molecular approaches of genetic engineering.
Gustafson, J.P., Raskina, O., Ma, X., Nevo, E. 2009. Evolutionary Genomics of Wheat. In: Carver, B.F. editor. Wheat: Science and Trade. Hoboken, NJ. Wiley-Blackwell. p. 5-30.
Gustafson, J.P., Ma, X., Korzun, V., Snape, J.W. 2008. A Consensus Map of Rye Integrating Mapping Data from Five Mapping Populations. Theoretical and Applied Genetics. 118:793-800.