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United States Department of Agriculture

Agricultural Research Service

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Research Project: Genetic Analysis of Complex Traits in Maize

Location: Plant Science Research

2013 Annual Report


1a.Objectives (from AD-416):
1. Develop novel maize genetic resources and analysis tools to enable high resolution dissection of complex agronomic traits.

1A. Create new genetic stocks to identify favorable alleles for yield improvement derived from exotic maize germplasm.

1B. Develop near-isogenic line (NIL) populations for the identification of disease resistance loci.

1C. Develop new strategies for the analysis of complex trait phenotypes.

2. Identify favorable alleles for disease resistance and agronomic traits in exotic maize germplasm.

2A. Geographic distribution of disease resistance alleles in maize.

2B. Enrichment of novel disease resistance alleles from exotic maize in adapted genetic backgrounds.

2C. Identifying new sources of resistance to Southern leaf blight (SLB), Fusarium ear rot, and fumonisin contamination from the GEM program and the NCSU tropical maize breeding program.

2D. Identify resistance loci from lines with elite levels of multiple disease resistance (MDR).

2E. Identification of disease resistance and yield genes from wild relatives.

3. Identify genes and mechanisms underlying quantitative disease resistance and defense response in maize.


1b.Approach (from AD-416):
1. Create new genetic stocks to identify favorable alleles for yield improvement derived from exotic maize germplasm. Develop near-isogenic line (NIL) populations for the identification of disease resistance loci. Develop new strategies for the analysis of complex trait phenotypes.

2. Geographic distribution of disease resistance alleles in maize. Enrichment of novel disease resistance alleles from exotic maize in adapted genetic backgrounds. Identifying new sources of resistance to Southern leaf blight (SLB), Fusarium ear rot, and fumonisin contamination from the GEM program and the NCSU tropical maize breeding program. Identify resistance loci from lines with elite levels of multiple disease resistance (MDR). Identification of disease resistance and yield genes from wild relatives.

3. Select candidate genes and order at least 50 insertional mutant lines. Screen plants for desired insertional events and self. Identify P. sorghi isolate that induces HR on the line W22.


3.Progress Report:
We developed BC5 generations of landrace introgression lines. We created and evaluated a set of experimental hybrids to identify appropriate testers to evaluate yield potential of these lines. We developed BC3F3 populations to fine-map resistance to quantitative disease resistances. We isolated DNA from 3 – 5 plants each of a set of more than 350 maize heirloom landrace varieties distributed from Canada to southern Chile and developed assays to evaluate their genetic variations at several candidate photoperiod genes. We planted an experiment to measure the direct response to recurrent selection for ear rot resistance and yield in a diverse corn population. We also crossed 100 lines from each of three selection cycles to an elite tester line to measure the effect of selection for improved performance in partly inbred lines on the performance of hybrids made from those lines. We planted experiments to screen GEM breeding lines for resistance to Fusarium ear rot and southern corn leaf blight resistances.

We have analyzed a number of distinct data sets to identify genes associated with resistance to southern corn leaf blight disease. Genes with repeatable associations across experiments are undergoing functional evaluation using insertional mutant analysis, gene expression analysis, and resequencing. We have begun to evaluate the NIL populatins developed for the identification of disease resistance loci. Several lines have been identified with enhanced resistance to multiple diseases.


4.Accomplishments
1. Identification of genes and pathways associated with the maize defense response. We created a series of specialized mapping populations which carried an autoactive defense response gene. Genome wide association analyses of these populations has identified a set of genes associated with protein degradation and programmed cell death which appear to be associated with the control of the hypersenstivie defense response in maize. This information is primarily of use to researchers trying to understand how this important defense response is controlled by the plant. Ultimately it may lead to improved disease resistant varieties created by transgenic or conventional approaches.


Review Publications
Willcox, M., Davis, G., Warburton, M.L., Windham, G.L., Abbas, H.K., Betran, J., Holland, J.B., Williams, W.P. 2013. Confirming quantitative trait loci for aflatoxin resistance from Mp313E in different genetic backgrounds. Molecular Breeding. 32(1):15-26.

Olukolu, B., Negeri, A., Dhawan, R., Venkata, B.P., Sharma, P., Garg, A., Gachomo, E., Marla, S., Chu, K., Hasan, A., Ji, J., Chintamanani, S., Green, J., Holland, J.B., Wisser, R., Shyu, C., Johal, G., Balint Kurti, P.J. 2013. A connected set of genes associated with programmed cell death implicated in controlling the hypersensitive response in maize caused by a maize auto-active resistance gene. Genetics. 193:609-620.

Veturi, Y., Kump, K., Walsh, E., Ott, O., Poland, J.A., Kolkman, J., Nelson, R., Balint Kurti, P.J., Holland, J.B., Wisser, R. 2012. Multivariate mixed linear model analysis of longitudinal data: an information-rich statistical technique for analyzing disease resistance data. Phytopathology. 102(11):1017-1025.

Hizbai, B., Gardner, K., Wight, C., Danda, R., Molnar, S., Johnson, D., Fregeau-Reid, J., Yan, W., Rossnagel, B., Holland, J.B., Tinker, N. 2012. Quantitative trait loci affecting oil content, oil composition, and other agronomically important traits in Oat (Avena sativa L.). The Plant Genome. 5:164-175.

Hung, H.Y., Holland, J.B. 2012. Diallel analysis of resistance to fusarium ear rot and fumonisin contamination in maize. Crop Science. 52:2173-2181.

Green, J., Appel, H., Rehrig, E., Harnsomburana, J., Chang, J., Chintamanani, S., Balint Kurti, P.J., Shyu, C. 2012. PhenoPhyte: A flexible affordable method to quantify visual 2D phenotypes. Plant Physiology. 8:45.

Benavente, L., Ding, X., Redinbaugh, M.G., Nelson, R., Balint Kurti, P.J. 2012. Virus-induced gene silencing in diverse maize lines using the Brome Mosaic virus-based silencing vector. Maydica. 57(3/4):206-214.

Last Modified: 10/20/2014
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