Applied Genomics
Our group is one of 17 groups across the nation that will participate in a Coordinated Agricultural Project (CAP) titled "Applied Wheat Genomics" (http://maswheat.ucdavis.edu/) with funding from the U.S. Department of Agriculture (USDA) Cooperative State Research, Education, and Extension Service (CSREES). The overall goal of this project is to transfer new developments in genomics to wheat improvement by combining the expertise of genomics researchers, wheat breeders, and end users. This multi-state, multi-institutional, and multi-disciplinary network of public wheat breeding programs and high-throughput genotyping laboratories will work together to discover new valuable quantitative trait loci (QTL) and genes of agronomic relevance and to rapidly deploy these into adapted varieties throughout the country using forward marker-assisted selection (MAS) strategies.
Strawbreaker foot rot or eyespot (caused by Tapesia yallundae and Tapesia acuformis) is a significant yield-limiting disease in wheat (Triticum aestivum)-growing regions of the U.S. Pacific Northwest (northeastern Oregon, eastern Washington, and northern Idaho). The most effective source of genetic resistance to eyespot is Pch1, a gene derived from one of wheat’s wild relatives, Aegilops ventricosa. Pch1 was introduced to breeding germplasm through the breeding line VPM-1 and an endopeptidase isozyme marker (Ep-D1b), tightly linked to Pch1, has been used to track resistance in breeding programs. Because a DNA-based marker would be more desirable for indirect selection, an AFLP-derived microsatellite marker, XustSSR2001, was developed by others and reported to be linked to Pch1. Unfortunately, we have found that XustSSR2001 does not show the tight linkage required for marker-assisted selection. Thus, the development of a DNA-based marker to replace the Ep-D1b isozyme marker is still needed. For these reasons, we initiated a project to better characterize the Pch1 region and to identify linked markers using a comparative genomics approach.
Publications
Riera-Lizarazu, O., C.J.W. Watson, R.S. Zemetra, C.A. Mallory-Smith, M.I. Vales. 2005. Development of a molecular marker linkage map of jointed goatgrass (Aegilops cylindrica Host). In: Agronomy Abstracts. ASA, CSSA, SSSA 2005 Nov. 6-10, Annual Meetings, Salt Lake City, UT.
Cephalosporium stripe of wheat (caused by Cephalosporium gramineum) and eyespot (caused by Pseudocercosporella herpotrichoides) are limiting factor in wheat production areas where soil and water conservation practices are exercised. In collaboration with Drs. Chris Mundt, M. Isabel Vales, and James Peterson, we are working on a project to use DNA-based markers and quantitative trait mapping to study the genetic basis of Cephalosporium stripe resistance and to identify molecular tags linked to resistance loci. Ultimately, molecular marker-assisted screening for resistance without the pathogen and marker-assisted transfer of resistance into common wheat cultivars adapted to Oregon may be feasible.
Publications
Rahman, M., C.C. Mundt, T.J. Wolpert, and O. Riera-Lizarazu. 2001. Sensitivity of wheat genotypes to a toxic fraction produced by Cephalosporium gramineum and correlation with disease susceptibility. Phytopathology 91:702-707.
Alien Gene Introgressions and Chromosome Engineering
Introgression of alien chromatin into wheat through wide crossing can widen the genetic base of wheat. However, a major locus on chromosome 5B of wheat, Ph1, prevents recombination between wheat and alien chromosomes. Thus, incorporation of interesting traits, such as disease resistance, from alien chromosomes requires specialized wheat stocks and chromosome engineering techniques. In collaboration with Dr. M. Isabel Vales, we are currently developing materials that lack Ph1 to induce recombination between wheat and alien chromosomes. Recombinant chromosomes will be identified using molecular markers and in situ hybridization. Wheat lines carrying chromosomes from Thinopyrum elongatum, Thinopyrum intermedium, and Thinopyrum ponticum that confer resistance to the barley yellow dwarf virus (BYDV), and Cephalosporium stripe (caused by C. gramineum) are the targets for introgression.