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Resistance

The Relationship Between Slow Rusting and a Specific Resistance Gene for Wheat Stem Rust. J. B. Rowell, Research plant pathologist (retired), Cereal Rust Laboratory, Agricultural Research Service, U.S. Department of Agriculture, University of Minnesota, St. Paul 55108; Phytopathology 71:1184-1186. Accepted for publication 9 March 1981. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1981. DOI: 10.1094/Phyto-71-1184.

Wheat cultivar Idaed 59 has specific resistance to Puccinia graminis f. sp. tritici conditioned by gene SrTt-1 that is associated with the resistance mechanisms of slow rusting and low receptivity to infection by rust races virulent for SrTt-1. The link between slow rusting and SrTt-1 purportedly was broken in a previous study in which a few progenies from Baart/Idaed 59 were characterized as having srTt-1 combined with slow rusting and SrTt-1 with fast rusting. The seedling responses of two such progenies were reexamined by infection tests with cultures of races 151-QSH and 15-TLM, which are avirulent and virulent on SrTt-1, respectively. The slow-rusting line resembled Idaed 59 in that it had the seedling resistance conditioned by SrTt-1 to race 151-QSH and low receptivity to infection by race 15-TLM. The fast-rusting line resembled Baart in that it was fully susceptible to both races. Thus, the resistance mechanisms in Idaed 59 have not been separated, and the relationships among them remain unclear.