Showing papers by "Scott D. Haley published in 2007"

Molecular Mapping of the Russian Wheat Aphid Resistance Gene Dn2414 in Wheat

Abstract: Russian wheat aphid (RWA) [Diuraphis noxia (Kurdjumov)] is an important pest of wheat (Triticum aestivum L.) in several production areas of the world. The most effective and economical approach for controlling RWA is to use resistant cultivars. A wheat line, ST-ARS 02RWA2414-11 (2414-11), showed a high level of resistance to RWA biotype 2. Our objectives were to map the resistance gene and develop polymerase chain reaction (PCR)-based markers for marker-assisted selection (MAS). A mapping population of 212 F 2 individuals was developed from a cross of 2414-11 and the susceptible cultivar Yuma. The F 2 individuals and F 2:3 families were infested using biotype 2 RWA. The RWA resistance of 2414-11 is controlled by a single major gene, provisionally designated as Dn2414. Using standard PCR, 30 marker loci were found to be linked to Dn2414 with recombination frequencies (θ) of 0.00 to 0.27 and logarithm of the odds to the base 10 (LOD) scores of 7.6 to 66.1. Of the 30 markers, 26 were tightly linked to Dn2414 with θ ≤ 0.05. A genetic map was constructed consisting of 31 loci spanning a region of 34.7 cM. The close link-age of Dn2414 with several rye chromosome 1R short arm (1RS)-specific simple sequence repeat markers and low θ values around the Dn2414 gene indicate that Dn2414 is located on chromosome 1RS.1BL (translocation chromosome with IRS and wheat chromosome 1B long arm). Phenotypic and marker profiles of 2414-11 and its relatives are the same as other lines known to carry Dn7. The Dn2414 gene is thus located on 1RS arm, and the large number of PCR markers will be valuable for MAS of this gene.

Registration of 'Ripper' Wheat

Abstract: Ripper' (Reg. No. CV-1016, PI 644222) hard red winter wheat (Triticum aestivum L.) was developed by the Colorado Agricultural Experiment Station and released in August 2006 through an exclusive marketing agreement with the Colorado Wheat Research Foundation. In addition to researchers at Colorado State University, USDA-ARS researchers in Manhattan, KS, and St. Paul, MN, participated in the development of Ripper. Ripper was selected from the cross CO940606/TAM107R-2 made in 1996 at Fort Collins, CO. CO940606 is an unreleased sib-selection of KS94WGRC29 (PI 586954), a germplasm release from Kansas State University with the pedigree PI 220127/P5//'TAM-200'/KS87H66, while TAM107R-2 is an unreleased sib-selection of the hard red winter wheat cultivar Prairie Red (PI 605390). Ripper was selected as an F 3:4 line (F 3 -derived line in the F 4 generation) in 2000 and assigned experimental line number CO00016. Ripper was released because of its superior grain yield performance under nonirrigated production in eastern Colorado and superior milling and bread-baking quality.

Resistance to Rhopalosiphum padi (Homoptera: Aphididae) in Triticale and Triticale-Derived Wheat Lines Resistant to Diuraphis noxia (Homoptera: Aphididae)

Abstract: Rhopalosiphum padi (L.) (bird cherry-oat aphid) and Diuraphis noxia (Mordvilko) (Russian wheat aphid) are common aphid pests of wheat and can cooccur at relatively high levels within wheat fields. Resistance to both aphids has been identified in several triticale accessions. We conducted experiments to identify and characterize antibiosis-type resistance to R. padi in additional triticale lines and to test R. padi-resistance levels in several backcrossed, triticale-derived lines of D. noxia-resistant wheat. Triticale accessions ‘6A-558’, ‘H85-734’ and ‘M86-6174’ were identified with moderate levels of antibiosis to R. padi. All three accessions limited R. padi population growth relative to ‘Arapahoe’ over 13 d. 6A-558 increased development time of R. padi compared to that on Arapahoe, and 6A-558, H85-734 and M86-6174 each decreased the number of nymphs produced by R. padi over 7 d. Additional tests confirmed ‘N1185’ triticale as a strong source of resistance to R. padi, and showed that ‘Lamar’ wheat was n...

Trait Associations at the Xgwm 261 and Rht-B1 Loci in Two Winter Wheat Recombinant Inbred Line Populations

Abstract: Microsatellite marker locus Xgwm 261 has been associated with reduced plant height attributed to the linked gibberellic acid (GA) sensitive Rht8c allele in wheat (Triticum aestivum L.). Our objective was to determine effects of allelic variation at the Xgwm 261 and Rht-B1 loci in two winter wheat recombinant inbred line (RIL) populations. ‘Longhorn’/’Akron’ and Longhorn/‘Yuma’ RIL populations were evaluated in controlled environments for GA sensitivity and coleoptile length and were grown in Colorado at fi ve locations for 2 yr for agronomic evaluation. Microsatellite markers were used to identify alleles at the Xgwm 261 and Rht-B1 loci. In both populations, the Rht-B1b class showed reduced plant height (8.9% average), GA sensitivity (average 73.5%), coleoptile length (average 11.3%), and test weight (average 1.9%) relative to the Rht-B1a class. In the Longhorn/Yuma population, Rht-B1b and

Genome level targeted breeding in wheat

Abstract: Molecular marker technologies offer a range of opportunities to plant breeders to improve the efficiency of breeding programs. The deployment of multiple genes relevant to a given environment is the major aim of a breeding program. To achieve this we describe a common approach and platform for MAS in wheat breeding programs, which we called this ‘genome level targeted breeding’. This approach would allow simultaneous selection of multiple target loci. The first aim is to establish a wheat map that includes important genes used in the breeding programs. The second is to maximize multiplexing ability for the marker screenings to be able to select for multiple traits, and the third is to discuss possible packaging option of the markers for specific breeding goals. The trait-based map may also serve a template to International Wheat Genome Sequencing Consortium for prioritising chromosomes and genomic regions while conducting physical mapping and eventually sequencing of wheat genome. Thus far, in collaboration with eight breeding programs including the CIMMYT, we have assembled a wheat map with the genomic locations of 85 genes. Additional breeding programs are expected to contribute to this process. For an initial study we have multiplexed 31 SSR markers for 22 traits and we have achieved this with having run each sample with two capillaries. We will describe and discuss various multiplexing options for specific breeding goals, different genotyping platforms, the use of bioinformatics tools for the generation of haplotype signatures for each trait and selection of lines for the breeders. Potential impact of the genome level targeted breeding on the breeding strategies will also be discussed.