Location: Plant Science ResearchTitle: Introgression of rpg4/Rpg5 into barley germplasm provides insights into the genetics of resistance to stem rust race TTKSK
|HERNANDEZ, J - Oregon State University|
|STEFFENSON, B - University Of Minnesota|
|FILICHKIN, T - Oregon State University|
|FISK, S - Oregon State University|
|HELGERSON, L - Oregon State University|
|MEINTS, B - Oregon State University|
|VINING, K - Oregon State University|
|DEL BLANCO, ALICIA - University Of California|
|HAYES, P - Oregon State University|
Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/29/2019
Publication Date: 5/7/2019
Citation: Hernandez, J., Steffenson, B.J., Filichkin, T., Fisk, S.P., Helgerson, L., Meints, B., Vining, K.J., Marshall, D.S., Del Blanco, A., Chen, X., Hayes, P.M. 2019. Introgression of rpg4/Rpg5 into barley germplasm provides insights into the genetics of resistance to stem rust race TTKSK. Phytopathology. 109:1018-1028.
Interpretive Summary: Ug-99 stem rust is an important disease of barley throughout the world. Immunity to the disease does bot exist in barley. However, partial resistance is expressed in some barley lines and varieties when the plants are seedlings, and in other lines once the plants enter their reproductive growth stage. The latter type of resistance is referred to as adult-plant resistance. In this study, both seedling and adult-plant resistance to Ug-99 stem rust was evaluated on several double-haploid populations. The adult-plant resistance was evaluated over 2 years in Njoro, Kenya, and was found to be highly effective in reducing the severity of the disease.
Technical Abstract: Stem rust (incited by Puccinia graminis f.sp tritici) is a major disease of wheat and barley. The highly virulent African race TTKSK of stem rust is of particular concern because most cultivars are susceptible. In order to prepare for the possible arrival of stem rust race TTKSK in North America, we crossed a range of barley germplasm - representing different growth habits and end-uses - with donors of Rpg1 and rpg4/Rpg5. The former confers resistance to prevalent races of stem rust in North America and the latter confers resistance to race TTKSK. We produced doubled haploids from these crosses and determined their allele type at the Rpg loci and haplotype at 9,000 SNP loci. The doubled haploids were phenotyped for TTKSK resistance at the seedling stage. Integration of genotype and phenotype data revealed that: (1) Rpg1 was not associated with TTKSK resistance; (2) rpg4/Rpg5 was necessary but not sufficient for resistance; and (3) specific haplotypes at two QTLs were required for rpg4/Rpg5 to confer resistance to TTKSK. Adult plant resistance to leaf rust and stripe rust (incited by P. hordei and P. striiformis f.sp. hordei, respectively) was also assessed on the doubled haploids in field trials at three locations in the USA over a two-year period. Adult plant resistance to TTKSK was assessed on a subset of the doubled haploids in Kenya. Doubled haploids were identified with resistance to all three rusts, and this germplasm is available to the research and breeding communities.