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United States Department of Agriculture

Agricultural Research Service

Research Project: Genetics and Genomics of Complex Traits in Grain Crops

Location: Plant Genetics Research

2013 Annual Report


1a.Objectives (from AD-416):
Objective 1: Create novel genetic resources for complex trait dissection in diverse maize germplasm. • Sub-objective 1.1: Create, genotype, and phenotype doubled haploid (DH) lines from a synthetic population containing diverse germplasm, including teosinte alleles. • Sub-objective 1.2: Create, genotype and phenotype novel quantitative trait loci (QTL) populations derived from a (teosinte x B73) x B73 population. Objective 2: Characterize the genetic basis of important agronomic traits (heterosis, drought tolerance, yield components, DIMBOA synthesis, and kernel composition) in maize. • Sub-objective 2.1: Determine the genetic basis of heterosis and its relationship to recombination and the Hill-Robertson effect. • Sub-objective 2.2: Fine-map the regulatory site for the major QTL of DIMBOA synthesis for chromosome 4 from CI31A. • Sub-objective 2.3: Fine map the genes responsible for a KRN QTL on chromosome 2 and a KWT QTL (specific QTL to be chosen based on 2012 data) in a teosinte x maize population. • Sub-objective 2.4: Determine the genetic basis of kernel composition in maize x teosinte introgression libraries, and compare the QTL and effects to those observed in maize. Objective 3: Determine molecular and biochemical mechanisms of drought tolerance in maize and model species. • Sub-objective 3.1: Determine the expression patterns of transcription factor (TF) genes in the drought response of maize. • Sub-objective 3.2: To fully characterize the molecular genetic basis of the conserved interplay between reactive oxygen species (ROS) and amino acid metabolism, linked through gamma-glutamyl amino acids (GGAA) metabolism and transport, and the role of GGAA metabolism in dehydration tolerance. Objective 4: Identify and curate key datasets that will serve to benchmark genomic discovery tools for key agronomic traits, especially response to biotic and abiotic environmental stressors. • Sub-objective 4.1: Bring into The Maize Genome Database (MaizeGDB) the phenotypic data generated by critically important research endeavors including the Maize Diversity Project. • Sub-objective 4.2: Curate maize metabolism and pathways data for release as a BioCyc database and as GO annotation files. Objective 5: Characterize the relationship between root biology and drought tolerance in wheat and related species. • Sub-objective 5.1: Elucidate the physiological basis of root growth responses in wheat (hard and soft red winter) and the “wheat model” Brachypodium distachyon, to imposed water deficits.


1b.Approach (from AD-416):
Create and fully describe double haploid lines and QTL populations for complex trait dissection. Map and characterize yield QTLs to interrogate the genetic basis of heterosis in maize. Use QTL fine mapping protocols to define the genetic regulation of DIMBOA synthesis in maize. Develop targeted metabolomic profiles to define the role of nitrogen metabolism in establishing dehydration tolerance in the C4 grasses, including maize. Combine field experiments and transgenic maize lines to determine the role of selected transcription factors in the response of roots to water deficits and their possible role in drought tolerance. Use modern curation tools to improve the phenotype to gene utility of the MaizeGDB and improve linkages to other community database efforts.


3.Progress Report:
Although the project was only initiated in March of 2013 we have made progress in most of the objectives all of which are relevant to the NP 301 Action Plan. For the research associated with objectives 1 and 2, the planting of experimental materials was completed by the first week of June 2013. The tissue collection will be completed for the analysis of field drought effects on root transcription factor expression. We established protocols and experimental infrastructure for the labeling of metabolites with stable isotopes as part of our characterization of the molecular genetic basis of conserved dehydration responses in grasses (objective 3). We prepared maize gene function training data sets to support development of tools for both automated extraction of gene functions from the literature, with the goal to support facile integration into genome databases such as MaizeGDB (objective 4). This project is affiliated with the international BioCreative consortium, which is a collaboration of database curators from several model plant and animal species: maize [MaizeGDB], Arabidopsis, Drosophila, mouse and rat. Our progress on root responses to water deficit stress in wheat has been limited. However, we have established sources for the necessary germplasm required for the planned study (objective 5).


Last Modified: 10/24/2014
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