Quantitative Determination of the Gene Action of Leaf Rust Resistance in Four Cultivars of Wheat,Triticum aestivum

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Abstract
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 population 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 Wamptum and Wared. Based on joint scaling test, 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 .times. 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.