Sources and genetics of Septoria speckled leaf blotch resistance in Hordeum
2004
Steffenson, B. | Zhong, S. (University of Minnesota (USA). Department of Plant Pathology) | Toubia-Rahme, H. (Institute for Agrobiotechnology, Tulln (Austria). Department of Plant Biotechnology) | Fetch, T.G. (Agriculture and Agri-Food Canada, Winnipeg, Manitoba (Canada). Cereal Research Centre) | Pickering, R. (New Zealand Inst. for Crop and Food Research Limited, Christchurch (New Zealand))
Septoria speckled leaf blotch (SSLB), caused by Septoria passerinii, has become one of the most serious diseases of barley in the Upper Midwest region of the USA. Deployment of resistant cultivars is the most economic and environmentally sound means of preventing SSLB epidemics. To effectively breed for SSLB resistance, it is important to obtain information about the number and chromosomal position of genes controlling the resistance. Thus, we initiated studies to elucidate the genetics of S. passerinii resistance in cultivated barley (accessions CIho 4780 and CIho 10644), wild barley (accessions Shechem 12-32 and Damon 11-11), and bulbous barley grass (recombinant accession 129F2). A single dominant gene was found to confer resistance in both CIho 4780 and CIho 10644. The gene (Rsp2) in CIho 4780 was mapped to the short arm of barley chromosome 5(1H) using molecular markers. A previous allelism test revealed the close linkage of Rsp2 in CIho 4780 with Rsp3 in CIho 10644. Our molecular mapping data confirmed the close linkage of these two genes on chromosome 5(1H). Resistance in the barley-bulbous barley grass recombinant line 129F2 was conferred by a single dominant gene that was positioned to chromosome 4(4H) by GISH and FISH and verified by Southern hybridization. Genetic analyses of the two wild barley crosses are in progress. Sources of resistance to S. passerinii are legion in the primary and secondary gene pools of Hordeum. The simple inheritance of resistance, coupled with the identification of user-friendly markers for the resistance genes, will facilitate the development of cultivars with broad-based SSLB resistance
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