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United States Department of Agriculture

Agricultural Research Service


item Mcvey, Donald
item Long, David

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/2/1992
Publication Date: N/A
Citation: N/A

Interpretive Summary: Wheat leaf rust can cause yield reduction without appearing to be a destructive disease. The use of resistant cultivars is the most economical means of controlling this disease. Thirty commonly grown hard red winter wheat cultivars and 56 breeding lines from nine hard red winter wheat breeding programs were evaluated for their resistance to leaf rust detectible in the seedling stage using 17 isolates of leaf rust, each with a different combination of genes for avirulence/virulence. Diversity of resistance among the cultivars is limited. No genes for resistance were detected in six cultivars, while another six cultivars were identified with the same single gene. None of the cultivars were resistant to all 17 rust isolates. Determining the genes for resistance to leaf rust present in these breeding lines provides information necessary to choose the best parents for the development of resistant cultivars with different combinations of genes for resistance. The development of cultivar populations with diverse genetic gene constitution makes it more difficult for the leaf rust population to overcome their resistances.

Technical Abstract: Lr genes for resistance to leaf rust (Puccinia recondita Roberge ex Desmaz. f.sp. tritici (Erikr. & E. Henn.)) were determined from infection-type data of the interaction of 30 hard red winter wheat (Triticum aestivum L.) cultivars and 56 breeding lines and wheat leaf rust. Infection-type data from seedlings infected with 17 isolates of leaf rust were used to determine low or high infection type. The gene-for-gene concept was used to identify corresponding gene pairs of the 16 genes for resistance tested for. Among the cultivars, Lr1, Lr3, Lr10, Lr14a, Lr16, Lr24, and Lr26 were postulated. Six cultivars were postulated to have only Lr24, and six were susceptible to all isolates. Among the breeding lines, Lr1, Lr2a, Lr3, Lr3ka, Lr9, Lr10, Lr11, Lr14a, Lr16, Lr17, Lr18, Lr24, Lr26, and Lr30 were postulated as present. Lr2c and Lr14b were not postulated as present. Lr2c and Lr14b were not postulated as present.

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