1CSIRO Plant Industry, GPO Box 1600, Canberra A.C.T. 2601, Australia; 2Plant Sciences, University of Western Australia, Nedlands W.A. 6907, Australia; 3Soil Science and Plant Nutrition, University of Western Australia, Nedlands W.A. 6907, Australia; 4INRA, Station d'Amelioration des Plantes, BP 2935650 Le Rheu, France
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Accepted 8 November 1999.
A resistance (R) gene-rich 2S chromosomal segment from Triticum ventricosum contains a cereal cyst nematode (CCN; Heterodera avenae) R gene locus CreX and a closely linked group of genes (Sr38, Yr17, and Lr37) that confer resistance to stem rust (Puccinia graminis f. sp. tritici), stripe rust (P. striiformis f. sp. tritici), and leaf rust (P. recondita f. sp. tritici) when introgressed into wheat. The 2S chromosomal segment from T. ventricosum is further delineated in translocations onto chromosome 2A of bread wheat, where the rust genes are retained but not the CreX gene. Using these critical genetic stocks, we have isolated family members of R gene analogs that are associated with either the 2S segment from T. ventricosum carrying the CreX locus or the rust genes. Derivatives of the Cre3 candidate R gene sequence and a rice (Oryza sativa) R gene analog that mapped to the 2S homologous chromosome groups in wheat were used to isolate related gene sequences from T. ventricosum that contain a nucleotide binding site-leucine rich repeat domain. The potential of these gene sequences as entry points for isolating candidate genes or gene family members of the CreX or rust genes and their further applications to plant breeding are discussed.
linked rust genes,
wheat genetic stocks.
© 2000 The American Phytopathological Society