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Genetic Mapping and Components of Resistance to Cercospora Zeae-Maydis in Maize
Gordon, Stuart G.

2003, Doctor of Philosophy, Ohio State University, Horticulture and Crop Science.
Gray leaf spot of maize (Zea mays L.), caused by Cercospora zeae-maydis (Tehon & Daniels), can greatly reduce grain yield worldwide. This study evaluated a novel source of resistance to C. zeae-maydis in the US Corn Belt and the Republic of South Africa (RSA), linked molecular markers to resistance loci using selective genotyping, and examined the components of resistance, sporulation, lesion length and number of lesions. The resistant maize inbred, VO613Y, was crossed to the susceptible inbred, Pa405, to obtain a population of 144 F2:3 progeny lines. These lines were evaluated at Wooster, Ohio, USA, and Cedara, RSA, for resistance to C. zeae-maydis based on percent leaf area affected (PLAA). A selected F3:4 population, derived by self-pollination of resistant and susceptible F2:3 lines, was evaluated at two Ohio locations over two seasons and at Cedara. Simple sequence repeat, restriction fragment length polymorphisms and resistance gene analog molecular marker data were obtained and analyzed based on F2:3 and F3:4 PLAA means across all environments by Kruskal-Wallis and ANOVA single factor analyses and composite interval mapping. Lesion length measurement, lesion counts and lesion sporulation data were taken on 4 resistant F3:4 progeny lines, 4 susceptible F3:4 progeny lines, and the parents. Quantitative trait loci located on two chromosome arms, 2L and 4L, together explained 47% of the variance in the F2:3 generation and 55% in the F3:4 generation across environments. Spearman rank correlations demonstrated that genotypes retained their relative ranks across environments. VO613Y-derived resistance extended the incubation period, resulted in the presence of fewer lesions and shortened the length of lesions. Taken together, this resulted in a lower percent leaf area affected by gray leaf spot. VO613Y and its resistant progeny did not inhibit spore production compared to Pa405 and its susceptible progeny, but resistant maize genotypes should contain fewer lesions capable of producing spores. The total number of spores produced on resistant maize genotypes should therefore be less than that produced on susceptible ones. These results indicate that VO613Y possesses QTL that may be introgressed into elite maize lines and deployed effectively in both southern Africa and the US Corn Belt.
Richard Pratt (Advisor)

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Gordon, S. (2003). Genetic Mapping and Components of Resistance to Cercospora Zeae-Maydis in Maize. (Electronic Thesis or Dissertation). Retrieved from https://etd.ohiolink.edu/

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Gordon, Stuart. "Genetic Mapping and Components of Resistance to Cercospora Zeae-Maydis in Maize." Electronic Thesis or Dissertation. Ohio State University, 2003. OhioLINK Electronic Theses and Dissertations Center. 29 Aug 2015.

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Gordon, Stuart "Genetic Mapping and Components of Resistance to Cercospora Zeae-Maydis in Maize." Electronic Thesis or Dissertation. Ohio State University, 2003. https://etd.ohiolink.edu/

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