Durable Rust Resistance in Wheat

Objective 6: Developing and Optimizing Markers for Rust Resistance

A large number of inexpensive markers are necessary for mapping and cloning of genes linked to economically important traits and for implementation of efficient breeding methods for rapid development of rust resistant varieties. Wheat has one of the largest collections of ESTs for a major crop species but the least amount of genome sequence information and the fewest molecular markers. This is largely because marker development for wheat is complicated by polyploidy and low polymorphism, especially in cultivated germplasm.

Single-nucleotide polymorphism (SNP) markers have become the technology of choice for most organisms because of their high frequency, wide distribution in genomes, and adaptation to high multiplex detection systems. However, there are not enough SNP markers available for wheat. Consequently, this project will use a combination of microsatellite (SSR), sequence tagged site (STS), and Diversity Array Technology (DArT) markers for haplotyping, pyramiding, and mapping stem rust resistance genes.

The primary goal of this Objective is to identify robust markers for previously characterized and novel sources of stem rust resistance. This objective can be partitioned into four sub-objectives:

optimization of markers for previously characterized stem rust resistance genes
haplotyping uncharacterized rust resistant genotypes to infer novelty and to plan new mapping experiments
pyramiding novel sources of rust resistance
mapping novel sources of rust resistance.

Collaborating Scientists

Institution	Name (Scientist)	email	Phone
University of Minnesota	James Anderson	ander319@umn.edu	(612) 625-9763
ICARDA	Michael Baum	m.baum@cgiar.org	963-21-2213433/477
UC-Davis	Jorge Dubcovsky	jdubcovsky@ucdavis.edu	(530) 752-5159
CSIRO	Evans Lagudah	evans.lagudah@csiro.au	61-2-62465392
CIMMYT	Ravi Singh	R.SINGH@CGIAR.ORG	52 (55) 5804-2004
Cornell University	Mark Sorrells	Mes12@cornell.edu	607-255-2180

Useful links

Grain Genes, a database for Triticeae and Avecena: http://wheat.pw.usda.gov/GG2/index.shtml
MAS page at UC Davis for stem rust markers: http://maswheat.ucdavis.edu/protocols/StemRust/index.htm
References
Objective 6 Milestones

Note to Wheat Researchers World-Wide:
Our group is interested in collaborating with anyone who would like to contribute to the goals of this Objective and beyond. Please contact Mark Sorrells for more details (see contact information above).

Objective 6: Developing and Optimizing Markers For Rust Resistance
Activities	Outputs	Outcomes (Short- and Long-Term)
Activity 6.1 Optimization of markers for previously characterized rust resistance gene markers	Optimized markers for all genes from the primary gene pool providing effective stem rust resistance to maximize efficiency of the breeding program.	Short Term: Materials and information necessary for marker-assisted breeding. Long Term: Resources necessary for pyramiding rust genes for durable resistance.
Activity 6.2 Haplotyping uncharacterized rust resistant genotypes to infer novelty and to plan new mapping experiments	Haplotypes for major resistance loci of uncharacterized sources of stem rust resistance. Genetic relationship estimates among all uncharacterized sources of stem rust resistance.	Short Term: Information required for cross-referencing sources of rust resistance. Long Term: A catalog of all known sources of marker alleles linked to rust resistance genes
Activity 6.3 Pyramiding novel sources of rust resistance	Several different breeding populations homozygous for 2 or more stem rust resistance genes.	Short Term: Molecular markers for new sources of rust resistance for use in the breeding programs. Long Term: Resources necessary for developing varieties with durable quantitative rust resistance.
Activity 6.4 Mapping novel sources of rust resistance	Mapped QTL for new sources of rust resistance including newly identified sources as well as APR in 4 to 6 different mapping populations	Short Term: Molecular markers for new sources of rust resistance for use in the breeding programs. Long Term: Resources necessary for developing varieties with durable quantitative rust resistance.