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Genetics

Chromosomal Location of the Powdery Mildew Resistance Gene of Amigo Wheat. M. Heun, Plant geneticist, Institute of Agronomy and Plant Breeding, D-8050 Freising-Weihenstephan, West Germany, Present address: Department of Plant Breeding and Biometry, 252 Emerson Hall, Cornell University, Ithaca, NY 14853-1902; B. Friebe(2), and W. Bushuk(3). (2)Cytogeneticist, Institute of Agronomy and Plant Breeding, D-8050 Freising-Weihenstephan, West Germany; (3)NSERC research professor, Food Science Department, University of Manitoba, Winnipeg, Man., Canada R3T 2N2. Phytopathology 80:1129-1133. Accepted for publication 30 April 1990. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/Phyto-80-1129.

Powdery mildew resistance of Amigo wheat has been analyzed and mapped by combining F₂ segregation data with cytogenetic and storage protein analyses. It is concluded that the powdery mildew resistance of Amigo is regulated by one gene with conditioned dominance. Cytogenetic and electrophoretic analyses revealed that the complete wheat chromosome arm 1AS is missing in Amigo and has been replaced by the rye chromosome arm 1RS. No susceptible recombinant was found among 1,034 F₂ plants of crosses of Amigo with Pm3 resistant lines; Pm3 is known to be located on 1AS. Thus, the powdery mildew resistance gene of Amigo is assumed to be located on the rye chromosome 1RS translocated to wheat chromosome 1AL. The resistance pattern of Amigo is different from that of lines carrying gene Pm8. Free segregation of the Amigo resistance gene and Pm8 (located on 1RS of 1RS?1BL translocations) occurred. On the basis of these results, we propose the gene symbol Pm17 for the Amigo powdery mildew resistance gene.