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Kui Xiang 1, GuangTang Pan 1, Lana M. Reid 2, ZhiMing Zhang 1 and XiaoYang Zhu 2 A meta-analysis of QTL associated with ear rot resistance in maize Introduction.

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Presentation on theme: "Kui Xiang 1, GuangTang Pan 1, Lana M. Reid 2, ZhiMing Zhang 1 and XiaoYang Zhu 2 A meta-analysis of QTL associated with ear rot resistance in maize Introduction."— Presentation transcript:

1 Kui Xiang 1, GuangTang Pan 1, Lana M. Reid 2, ZhiMing Zhang 1 and XiaoYang Zhu 2 A meta-analysis of QTL associated with ear rot resistance in maize Introduction © Maize Research Institute, Sichuan Agricultural University, Yaan , Sichuan, P.R. China 2 Eastern Cereal and Oilseed Research Centre, Agricultural & Agri-Food Canada, Ottawa, Ontario, Canada K1A 0C6 Maize ear rot (ER) is one of the most prevalent types of maize disease worldwide. The three predominant ER diseases, Aspergillus ear rot (AER), Fusarium ear rot (FER) and Gibberella ear rot (GER), are responsible for the most disease-related reductions in yield and quality. Meta-analysis is a set of statistical procedures for synthesizing research results from a number of different studies. Many studies showed that QTL meta-analyses can be used to combine results from independent published QTL studies. Results and discussion Materials and methods Fourteen studies on maize ER QTL published from were used in the current study. In these studies, the resistance of maize was measured by kernels exhibiting visible symptoms that were converted to percent of infection such as rot and mycelial growth. QTL identified in one population evaluated in a given environment were defined as an experiment. The identified QTL were projected onto a reference map for meta-analysis. The original map position, logarithm of odds score, confidence interval and R 2 (% phenotypic variance explained by the given trait) of each QTL were used for projection. Information pertaining to all genetic maps was collected or estimated according to the published maps, then QTL in their original maps were projected on IBM2 neighbors 2008 (Intermated B73×Mo17 Map) using BioMercator v 2.1 (Arcade et al. 2004). Some controversial markers between original and reference maps were deleted from the analysis to ensure the accuracy of the projection (Chardon et al. 2004). Eighty-seven initial QTL were used in the meta-analysis, which resulted in 29 consensuses ER meta-QTL (MQTL) comprising 65 initial QTL and 22 remaining individual QTL. All these MQTL occurred on all chromosomes with the exception of chromosomes 9 and 10, with two to six initial QTL on each chromosome (Table 1). Ten MQTL pooled three initial QTL, while 13 MQTL pooled two initial QTL. References Arcade A, Labourdette A, Falque M, Mangin B, Chardon F, Charcosset A, Joets J (2004) Biomercator: Integrating genetic maps and QTL towards discovery of candidate genes. Bioinformatics 20:2324–2326 Chardon F, Virlon B, Moreau L, Falque M, Joets J, Decousset L, Murigneux A, Charcosset A (2004) Genetic architecture of flowering time in maize as inferred from quantitative trait loci meta-analysis and synteny conservation with the rice genome. Genetics 168:2169–2185 ER in maize is mainly associated with three types (AER, FER and GER) based on the pathogen causing the ear rot. From meta-analysis, most MQTL consisted of two or three types of ER resistance. Eleven of 29 MQTL contributed to both FER and GER on chromosomes 1 to 7, especially on chromosomes 2 and 3, suggesting that there were some common QTL/genes for FER and GER resistance in these regions. Based on 29 MQTL, a total of 21 genes were found to be co- located within 2 cM of identified MQTL positions, located on 13 MQTL (1, 3, 4, 8, 10, 11, 14, 15, 16, 21, 22, 25 and 26). MQTLChrom.Number of Projected QTL Type of ER a MQTLChrom.Number of projected QTL Type of ER a 112FER, GER1652FER 212FER, GER1753FER, GER 312GER1853AER, FER, GER 423FER, GER1962FER 523FER, GER2062FER 623FER, GER2162FER,GER 733AER, FER2262FER 836FER, GER2362AER, FER 936AER, FER, GER2472FER 1032AER, FER2572FER, GER 1133AER, FER, GER2673FER, GER 1233AER, FER, GER2773GER 1345AER, FER2874GER AER, FER29 82 FER 1544FER, GER Table1 Characteristics of detected meta-QTL (MQTL) for ear rot (ER) resistance Fig. 1 Projection on a reference map of chromosome 2.08 and 3.04 of MQTL for ear rot resistance in maize. The name of MQTL are on the left; names of markers and the distances in centimorgans are on the right. Acknowledgement The authors gratefully acknowledge Dr Yu-Ming Wei from Sichuan Agricultural University for excellent advice on QTL meta-analyses. In this study, bins 3.04 and 2.08 were major QTL containing regions of ER resistance (Fig. 1). Three MQTL (MQTL 8, 9 and 10) were located on bin 3.04, while another three MQTL (4, 5 and 6) were derived from bin Further fine mapping should be worthwhile in the two regions. a AER = Aspergillus ear rot, FER = Fusarium ear rot, GER = Gibberella ear rot


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