Multi-Locus Mixed Model Analysis Of Stem Rust Resistance In Winter Wheat

Area of Science:

• Plant genetics
• Agricultural science
• Molecular biology

Background:

• Stem rust, caused by *Puccinia graminis* f. sp. *tritici*, poses a significant threat to global wheat production.
• Genome-wide association mapping (GWAS) is crucial for identifying genetic variants associated with desirable traits like disease resistance.
• High-throughput genotyping enables cost-effective mining of germplasm for beneficial alleles in crop improvement.

Purpose of the Study:

• To explore the genetic basis of stem rust resistance in a global collection of hexaploid winter wheat.
• To identify marker-trait associations for field resistance to North American races and seedling resistance to specific races (TTKSK, TRTTF, TTTTF, BCCBC).
• To evaluate the effectiveness of multi-locus mixed models for identifying loci with breeding applications.

Main Methods:

• Utilized a global collection of 1411 hexaploid winter wheat accessions.
• Genotyped accessions using 5390 single nucleotide polymorphism (SNP) markers.
• Applied multi-locus mixed models for association mapping to identify resistance loci.

Main Results:

• Identified ten high-confidence stem rust resistance loci.
• Confirmed SNP markers linked to known resistance genes *Sr33* and *Sr35*.
• Discovered at least three novel resistance loci suitable for introgression into elite wheat cultivars.

Conclusions:

• Multi-locus association mapping enhances the identification of genetic loci for crop improvement.
• The identified resistance loci offer valuable genetic resources for breeding wheat varieties with durable stem rust resistance.
• This research provides a practical approach for breeders to introgress rare alleles conferring disease resistance into elite wheat lines.