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Title:Genetic architecture of multiple disease resistance in one maize chromosome segment substitution line population
Author(s):Qiu, Yuting
Advisor(s):Jamann, Tiffany M.
Department / Program:Crop Sciences
Discipline:Crop Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Multiple disease resistance
QTL mapping
Foliar disease.
Abstract:Maize is one of the most important crops and is grown all over the world. Like other plants, maize is attacked by numerous pathogens. Diseases account for 2 to 15% of maize yield losses annually, and foliar diseases are the most destructive in terms of yield. With an increasing world population, utilizing host plant resistance is an environmentally and economically friendly solution to assure food security. Maize is susceptible to numerous diseases. Thus, breeding multiple disease resistant (MDR) varieties is critical. While the genetic basis of resistance to multiple fungal pathogens has been studied in maize, less is known about the relationship between fungal and bacterial resistance. Bacterial leaf streak (BLS) is a foliar disease of maize caused by Xanthomonas vasicola pv. vasculorum. Since the first report of BLS in the United States in 2014, this disease has spread all over the Midwestern corn belt. Little is known about the disease cycle, and consequently, management is difficult. Host resistance will likely play a major role in controlling the disease, as there is no practical chemical control. Thus, we conducted quantitative trait locus (QTL) mapping for BLS resistance in three maize populations: the Z022 (B73 × Oh43 recombinant inbred line) NAM population, the Z023 (B73 × Oh7B recombinant inbred line) NAM population, and the DRIL78 (NC344 × Oh7B chromosome segment substitution line) population. A total of five QTL were detected across two of the mapping populations. One of the detected QTL for BLS resistance in the DRIL78 population, located in chromosomal bin 4.07, overlaps with a region that has also been identified for southern corn leaf blight (SCLB) resistance in this same population. These data will be useful for developing maize varieties resistant to BLS and to mitigate the impact of bacterial leaf streak on maize production. Goss’s bacterial wilt and blight (GW) is an important foliar disease caused by Clavibacter nebraskensis. We evaluated an introgression line population, DRIL78, for GW in three different environments and conducted quantitative trait locus (QTL) mapping for each environment separately, as well as for the combined environments. We identified a total of ten QTL across multiple environments. We obtained the phenotypic data from the DRIL78 population for three additional foliar diseases: northern corn leaf blight (NCLB), southern corn leaf blight (SCLB) and gray leaf spot (GLS) and conducted mapping analysis using the same methods. Multivariate analysis was then conducted to identify regions conferring resistance to multiple diseases. We identified 20 chromosomal bins with putative multiple disease effects. We identified five chromosomal regions (bin 1.05, 3.04, 4.06, 8.03, and 9.02) with the strongest statistical support for a role in MDR. By examining the phenotypic effects of each haplotype, we identified several regions associated with increased resistance to multiple diseases and three regions associated with opposite effects for bacterial and fungal diseases. Several promising candidate regions for multiple disease resistance in maize were identified in this study. The results presented in this thesis are useful for both breeding and to understand the basic biology of host plant resistance. I identified both single disease and MDR QTL, which will serve as a foundation for subsequent fine mapping analysis and can be useful for breeding resistant varieties.
Issue Date:2020-05-06
Rights Information:Copyright 2020 Yuting Qiu
Date Available in IDEALS:2020-08-26
Date Deposited:2020-05

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