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Genetics

Quantitative Determination of the Gene Action of Leaf Rust Resistance in Four Cultivars of Wheat, Triticum aestivum. M. E. Bjarko, Graduate student, Department of Plant Pathology, Washington State University, Pullman 99164-6430; R. F. Line, Plant pathologist, Agriculture Research Service, U.S. Department of Agriculture, Pullman 99164-6430. Phytopathology 78:451-456. Accepted for publication 19 October 1987. 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, 1988. DOI: 10.1094/Phyto-78-451.

Gene action for resistance to leaf rust (Puccinia recondita) of wheat (Triticum aestivum) was studied in field plots using parental and F₁, F₂, and backcross plant populations from crosses of two slow-leaf-rusting cultivars (Borah and Wampum), a highly resistant cultivar (Wared), and a susceptible cultivar (Twin). Leaf rust intensity data were transformed to area under the disease progress curve (AUDPC). The inheritance of resistance as measured by AUDPC was recessive in Borah and partially recessive in Wampum and Wared. Based on joint scaling tests, inheritance of leaf rust resistance in Wampum best fit a simple additive genetic model with no dominance or epistatic interaction; resistance in Wared best fit an additive-dominance model with no epistatic interaction; and resistance in Borah was best explained by a genetic model assuming significant additive × additive interaction. In crosses between the resistant cultivars, resistance was additive and the gene action was best explained by genetic models assuming significant interaction components. No significant differences were found between reciprocal F₁ or F₂ generations of any cross, indicating the absence of cytoplasmic inheritance for leaf rust resistance in these cultivars.