The use of differential isolates of Rhynchosporium secalis to identify resistance to leaf scald in barley
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The presence of seedling resistance to leaf scald in Australian barley varieties and breeding lines has been determined using differential pathotypes of Rhynchosporium secalis. The previously described resistance genes Rrs1, Rrs2 and Rh4/Rh10 have been identified as well as other resistance sources that show different reactions against the isolates. Seedling resistance in the barley variety Skiff, Rh Skiff, has been found to react in an identical fashion to seedling resistance in the variety Barque suggesting the same gene/allele is present in these varieties. Virulence in R. secalis has been detected against almost all barley resistance sources tested, reinforcing previous experience that single gene resistance to scald is not a safe option. The differential isolates are being used to detect resistance genes in breeding lines as a service to barley breeding programs. They are also being used to detect novel resistances and will prove useful to breeders in building gene pyramids to try and develop varieties with more durable resistance.
KeywordsHordeum vulgare Spontaneum Virulence Rrs1 Rrs2
Lindy Scott for helping to establish the differential isolates and Felicity Keiper for helping to improve the screening system. Grant Hollaway (Department of Primary Industries, Victoria), Celeste Linde (Australian National University) and others for providing isolates. The Australian Winter Cereals Collection and also Christy Grimes and Tefera Tolera Angessa of the University of Western Australia for providing seed of barley varieties and accessions. Pamunkey was made available through the USDA National Small Grains Collection.
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