| | Twenty-four barley cultivars/lines including four differentials viz. Hannchen (harboring at least Ruh 1), Excelsior (harboring at least Ruh 2), Plush (harboring at least Ruh 6) and Odessa (universal susceptible to all races) were screened with six isolates of Ustilago hordei harboring known avirulence/virulence genes. Haploid basidiospore isolates with defined genotypes and of opposite mating type were mixed, inoculated on surface-sterilized seeds and screened twice per combination in greenhouse tests. Most present day barley cultivars carry resistance gene Ruh1 while some also have Ruh2 or Ruh6. CDC Candle, HB328, HB348 and Harrington were susceptible to all isolates. No cultivar/line was immune to all. This confirms our early findings that covered smut resistance in barley is not complete. However, several cultivars viz. TR244, Q21861, TR246, CDC Dolly, CDC Helgason were resistant to most isolates and could be used as resistance sources.
Fifty six doubled-haploid lines from the HT population used in the North American Barley Genome Mapping Project (NABGMP) were inoculated with a mated mixture representing genotype (V1V1v2v2v6v6). Such genotype is avirulent on Hannchen (Ruh1) and virulent on Excelsior (Ruh2) and Plush (Ruh6). TR306 is resistant and Harrington is susceptible. The 56 lines including the parents and checks were screened in the field in summer 2002. Thirty putative resistant lines were re-screened in the greenhouse to confirm their reaction. Three lines were susceptible. Based on field and greenhouse tests, lines segregated into 27R: 29S not significantly different from a 1: 1 ratio ( 2= 0.07, P=0.79) indicating a single major gene (Ruh1) in TR306. Ruh1 was mapped to the short arm of chromosome 1 (7H) between the markers iPgd1A and BCD129 on the HT map using MAPMAKER. This gene is different from the previously mapped covered smut resistance gene Ruhq on the short arm of chromosome 5 (1H) (Grewal et al. 2002). Efforts will be made to identify and map Ruh2 and Ruh6 by screening segregating barley populations with isolates harboring avirulence genes corresponding to these resistance genes. Molecular markers linked to these resistance genes will be identified and used in marker-assisted selection and pyramiding of these genes in elite barley lines.
Tajinder S. Grewal1, Brian G. Rossnagel1, Guus Bakkeren2 and Graham J. Scoles1
1 Department of Plant Sciences/Crop Development Centre, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK S7N 5A8
2 Agriculture & Agri-Food Canada, Pacific Agri-Food Research Centre, Summerland, BC, V0H 1Z0
Presented at the 3rd Canadian Barley Symposium, June 19-20, 2003 |
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