UG99 Stem rust (aka TTKSK, African stem rust races in the UG99 lineage)

We are working with colleagues at the USDA-ARS Forage Seed and Cereal Research Unit , Corvallis, OR; ARS, Raleigh, NC; and University of Minnesota - St. Paul, MN to characterize levels of barley seedling and adult plant resistance to stem rust UG99, identify the QTLs/genes responsible for the resistance phenotype, and to deploy resistance alleles in new genetic backgrounds. Thanks to USDA-ARS NACA funding. 

 

 

In this project, we are developing UG99-resistant resistant germplasm. By leveraging resources provided by the Barley Stripe Rust NACA, we are also assessing this germplasm for resistance to other rusts. We are now into our fourth cycle of doubled haploid resistance allele introgression and deployment. To access phenotype and genotype data, please send a request*  for access to the Box folder containing a treasure trove of phenotype and genotype data.

Cycle 1

  • Parents

Resistance donors: The donors were spring habit varieties, both hulled (TR02272, SB97197) and hull-less (MC0181-11, MC0181-31, SH98076, SH98073). This germplasm was developed by Drs. Brian Rossnagel and Aaron Beattie (University of Saskatchewan) and Bill Legge (Agriculture and Agri-food Canada, Manitoba). Seed of each accession, harvested from plants verified for resistance phenotype, was provided by Dr. Brian Steffenson (University of Minnesota).
Adapted germplasm:  The rpg4/Rpg5 donors were crossed with a range of germplasm from the OSU Barley Breeding Program, including winter and spring growth habit; hulled and hull-less; 2-row and 6-row; malting and food types.

  • Doubled haploid germplasm array

123 doubled haploids were generated from 14 cross combinations among the Cycle 1 parents. Genotype data were generated using the Illumina 9K and allele-specific primers for Rpg1 and rpg4/Rpg5. Phenotype  data for UG99 resistance at the seedling stage were generated at the Steffenson lab (University of Minnesota). 

Cycle 2

  • Parents

Resistance donors: The donors were TTKSK-resistant selections from Cycle I.
Adapted germplasm:  The Cycle I selections were crossed with winter/facultative malting and multi-use germplasm from the OSU program and the UC Davis Program.

  • Doubled haploid germplasm array

384 doubled haploids were generated. The DH and parents were genotyped with the Illumina 50K and allele-specific genotyping was conducted for rpg4/Rpg5. The array was phenotyped for TTKSK resistance at the seedling stage and for QCC-J resistance at the adult stage at the Steffenson lab (University of Minnesota). 

Cycle 3

  • Parents

Resistance donors: The donors are OSU Barley Breeding Program lines that exhibited resistance to race TTKSK at the seedling stage evaluations. None of these lines amplified for rpg4/Rpg5. These are potential new resistance sources.
Adapted germplasm: The Cycle 3 resistance donors were crossed with winter/facultative malting and multi-use germplasm from OSU Barley Breeding Program.

  • Doubled haploid germplasm array

373 doubled haploids were generated. Genotyping and phenotyping are in progress.

Cycle 4

  • In progress

Additional Outcomes:

*Please send requests for data access, and any questions/suggestions to franciscojavier.hernandezvasquez@oregonstate.edu