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Genetics

Gene Action for Inheritance of Durable, High-Temperature, Adult-Plant Resistance to Stripe Rust in Wheat. E. A. Milus, Former graduate student, now with Rohm and Haas Seeds, P.O. Box 111, Berthoud, CO 80513; R. F. Line, plant pathologist, Agricultural Research Service, U.S. Department of Agriculture, Department of Plant Pathology, Washington State University, Pullman 99164-6430. Phytopathology 76:435-441. Accepted for publication 14 October 1985. 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, 1986. DOI: 10.1094/Phyto-76-435.

Gaines, Nugaines, and Luke winter wheat cultivars have durable, high-temperature, adult-plant resistance to Puccinia striiformis. Parental, F₁, F₂, and backcross populations from reciprocal crosses between individual plants of resistant cultivars and with individual plants of a susceptible line were evaluated in the field. Rust intensity on each of approximately 8,000 plants was recorded three times during the season, and areas under disease progress curves were calculated from the intensity data. Resistance in the three cultivars was partially recessive (susceptibility was partially dominant) with no maternal inheritance. Epistatic gene action for resistance was significant in Nugaines, but most gene action among loci was additive. Epistatic gene action for susceptibility was detected in Luke, but its probability was lower than the probability for epistatic gene action in Nugaines. The proportion of susceptible progeny was higher than expected in the Gaines x susceptible cross, and gene action among loci in Gaines was not clear. The differences between Gaines and Nugaines were not due to epistatic gene action. Resistance genes in Luke were different from resistance genes in either Gaines or Nugaines.