Progress 10/01/10 to 09/30/15
Outputs
Target Audience:Products of this research impact private sector seed companies that are breeding for higher grain yield and tolerance to environmental stress, ingredient companies that use corn-based materials such as starch, oil and protein and consumers of corn as a source of nutrition. In addition, training efforts that are part of this research reach high school, undergraduate and graduates students. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? We have had sixgraduate students complete their PhDs who now work in the private sector for AgReliant Genetics, Dow AgroSciences, and Dupont - Pioneer Hi-Bred. One graduate student completed an MS degree and is now working on a PhD. Fivegraduate students completed their MS degree. FourMS students and fourPhD students are currently on the project, as well as two postdoctoral researchers. How have the results been disseminated to communities of interest?Through peer reviewed journal publications, press releases, talks at professional meetings, guest lectures, invited seminars. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
We have gained further in formation on the role of environment on plant development and response to and tolerance to stress. We have mapped extensive sets of chromsome regions and candidate genes for a broad series of traits that could be used to enhance efficiency of crop improvement.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
Brenda F. Owens, Alexander E. Lipka, Maria Magallanes-Lundback, Tyler Tiede, Christine H. Diepenbrock, Catherine B. Kandianis, Eunha Kim, Jason Cepela, Maria Mateos-Hernandez, C. Robin Buell, Edward S. Buckler, Dean DellaPenna, Michael A. Gore, Torbert R. Rocheford. 2014. A Foundation for Provitamin A Biofortification of Maize: Genome-Wide Association and Genomic Prediction Models of Carotenoid Levels. GENETICS Dec;198(4):1699-716.
|
Progress 10/01/13 to 09/30/14
Outputs
Target Audience: Products of this research impact private sector seed companies, ingredient companies that use corn-based materials such as starch, oil and protein and consumers of corn as a source of nutrition. In addition, training efforts that are part of this research reach high school, undergraduate and graduates students Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? We have had three graduate students complete their PhDs who now work in the private sector for AgReliant Genetics, Dow AgroSciences, and Dupont - Pioneer Hi-Bred. One graduate student completed an MS degree and is now working on a PhD. Three MS students and three PhD students are currently on the project, as well as two postdoctoral researchers. How have the results been disseminated to communities of interest? Through talks at regional, national and international professional meetings and through abstracts, and through journal publications, particularly for the nutritional traits. What do you plan to do during the next reporting period to accomplish the goals? Continue the field studies so that we can study genotype by environment interactions over more years. Perform more detailed genomic and genetic anlayses to better understand the genetic basis of these traits. Continue marker assisted selection programs.
Impacts
What was accomplished under these goals?
Overall Goals 1. Use molecular marker mapping approaches and genomic technologies to identify and characterize quantitative trait loci for important maize agronomic traits such as grain yield, grain moisture at harvest, tassel and ear inflorescence architecture, heat tolerance and functional stay-green. Pyramid favorable alleles of quantitative trait loci through marker assisted selection. 2. Use molecular marker mapping approaches and genomic technologies to identify and characterize quantitative trait loci for the important maize grain nutritional traits carotenoids (Vitamin A), tocopherols (Vitamin E) and starch digestibility. Pyramid favorable alleles of quantitative loci through marker assisted selection. What was accomplished under these goals? To understand the extent of the influence of environment on newly developed genotypes, genotypes must be tested in diverse environments using multi-environmental trials (MET) before their commercial release into a particular target environment. Modern plant breeding evaluation techniques use augmented field designs with unreplicated test genotypes in MET. We evaluated nested random regression models (NRRMs) to estimate GxE interactions and to identifying environmental indices responsible. Computer simulation studies showed that MET studies with more than 10 locations and 30 and 800 genotypes can be evaluated using these NRRM models. Based on the information obtained from NRRMs, we developed strategies for efficiently clustering locations to produce homogenous performance while commercialization of test genotypes. Based on these results, NRRMs were used to assess GxE from real METs conducted in various zones across the United States Corn Belt. These results showed that the Northern Corn Belt was most influenced by environmental characteristics during the vegetative stages while those in the Central Corn Belt were influenced by environmental conditions from the vegetative throughout the grain filling stages also. The identification of environmental factors that influence GxE and the use of these factors to clustering locations can provide better information in decision making while commercialization of chosen test genotypes. Genetic analysis of the stay-green trait was conducted in several populations of maize to define the genetic mechanisms associated with this drought tolerance phenotype. In one genetic study, two advanced backcross recombinant inbred mapping populations were created with Mo20W as one parent and B73 and Mo17 as the recurrent parents. These populations were tested under drought and high temperature stress conditions. Quantitative trait loci for the ratio vegetative index and photosystem II operating efficiency during grain fill were discovered on chromosomes one, two, three, four, six, and nine. Lines selected from the mapping populations were used in a North Carolina II experiment to evaluate hybrid expression of the stay-green trait. The hybrids exhibited higher ratio vegetative index values during the grain fill period than hybrids synthesized from Mo17 and B73. Photosystem II operating efficiency was positively correlated with grain yield across environments. In another genetic study, a subset of the maize nested association mapping population was evaluated per se and in testcross combinations with PHZ51. Joint linkage mapping discovered several quantitative trait loci for the stay-green trait in these recombinant inbred families. The results of these studies suggest that genetic diversity for functional stay-green in maize exists in both the temperate and tropical germplasm pools. The diversity for this trait could be exploited for increasing abiotic stress tolerance in maize. Founders of the NAM population were evaluated for in vitro starch digestibility of both cooked and uncooked flour. Recombinant inbred mapping populations for lines identified as having more rapid digestibility of uncooked flour, a trait desirable both for livestock feed and for ethanol production, were evaluated further. At least two loci correlated with more rapid digestion were identified. In addition, lines with slower starch digestion in cooked flour (but not resistant to digestion) were identified for further study. The overall goal of this project is to use modern genomic technologies to develop new traits and elite new public sector inbred lines and hybrids having improved performance and nutritional value. A genome-wide association study (GWAS) in the maize AMES Association Panel is being conducted to determine the genetic basis of important nutritional characteristics, component traits of yield, and plant adaption traits. The AMES Panel is comprised of more than 2,000 maize inbred lines that are stored in the USDA Germplasm Resource Information System (GRIN). The panel is being evaluated for variation in plant height and maturity, tolerance to heat and drought stresses, ear and tassel architecture traits, and nutritional traits of maize grain including content of carotenoids (VitaminA), tocopherols (Vitamin E), protein, starch, oil, and amino acids. On-going field and laboratory studies show significant genetic variation for traits measured thus far. As phenotypic and genetic data are summarized, the genetic architecture of each trait will be evaluated using GWAS techniques. Another aspect of our research in enhancement of maize focuses on analyses of the Nested Association Mapping (NAM) population for genetic variation in plant height and maturity, tolerance to heat and drought stresses, source-sink interactions and impacts on plant productivity, and grain nutritional traits. The NAM population is comprised of a series of recombinant inbred line (RIL) populations produced from crosses between 25 diverse maize populations and B73, the reference genome of maize. In 2013, a subset of the maize NAM populations with flowering times similar to B73 as well as the founder lines of each population were evaluated to identify genes and genetic loci that impact drought tolerance of maize. Ongoing plant and grain phenotyping studies show significant genetic variation in plant growth and development characteristics as well as responses to heat and drought stresses. As these data are summarized, the genetic architecture of each trait will be evaluated by nested linkage mapping and GWAS to uncover the bases of key agronomic traits. Our research activities also focus on developing a better understanding of the genetic inheritance of agronomic performance traits in private-sector corn inbred lines. Agronomic traits of interest include grain yield, grain moisture at harvest, days to anthesis, plant height, and ear height. QTL mapping populations are being developed from crosses between various exPVP lines and testcrossed to produce hybrid mapping populations. These populations are being evaluated for variations in agronomic performance in multienvironment trials. The genotypic and phenotypic information are being used in selection programs to pyramid favorable genetic loci from both parents.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
Owens, B. F., Lipka, A. E., Magallanes-Lundback, M., Tiede, T., Diepenbrock, C. H., Kandianis, C. B. & Rocheford, T. R. (2014). A Foundation for Provitamin A Biofortification of Maize: Genome-Wide Association and Genomic Prediction Models of Carotenoid Levels. Genetics, -114.
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
Hauck, Andrew L., Johnson, G. Richard, Mikel, Mark A., Mahone, Gregory S., Morales, Jason, Rocheford, Torbert R. and Bohn, Martin O. (2014) Generation Means Analysis of Elite Ex-Plant Variety Protection Commercial Inbreds: A New Public Maize Genetics Resource
Crop Sci. 54:174189.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2014
Citation:
Tuinstra MR. 2014. Challenges and Opportunities for Enhancing Maize Adaption to Stressful Environments. 1st Workshop on Engineered Plants, 28-29 April, Ames, IA.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2014
Citation:
Tuinstra MR. 2014. Sorghum Trait Development Pipeline for Improved Food and Feed Value. Sorghum and Millet Innovation Lab Inception Meetings, 23-25 April, LHotel Royal, Saly, Mbour, Senegal.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2014
Citation:
Tuinstra MR. 2014. New Opportunties for Managing Cyanide Content of Sorghum Forages. Livestock, Forage and Grain Forum, 13 March, Indianapolis, IN.Tuinstra MR. 2014. Opportunities for Developing New Traits in Sorghum. Kansas State University, 3 March, Manhattan, KS.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2014
Citation:
Weil C. 2014. Sequence indexed point mutations and plant breeding. Plant Genomics Congress. 10-12 Sept, St. Louis, MO
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2014
Citation:
Weil C. 2014 Optimization of Growth for Food and Biofuel. Advances in Plant Genomics Online Event 7-8 October, London UK
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2014
Citation:
Zaidi PH, Babu R, Vinayan MT, Seetharam K, Tuinstra MR. 2014. Developing Stress-Resilient Maize for Asian tropics. Abstract 276-5. ASA-CSSA- SSSA Annual Meetings, 2-5 November, Long Beach, CA.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2014
Citation:
Tuinstra MR. 2014. Functional Genomics Platform for Sorghum Crop Improvement. University of Queensland, 6 August, Brisbane, Australia.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2014
Citation:
Tuinstra MR, Johal G. 2014. Dissecting Heat Tolerance in Maize. 2nd Annual Review & Planning and Project Steering Committee Meeting of the Heat Tolerant Maize for Asia (HTMA) Project, 22-23 July, University of Agricultural Sciences (UAS), Raichur (Karnataka), India.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2014
Citation:
Busche M 2014 Investigation of Genes Influencing High Protein Digestibility in Sorghum bicolor. Genomics Center at Rice University Symposium, 4-5 October, Houston TX
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2014
Citation:
Lau K and Weil C. 2014. Examining the phenotypes of three developmental mutants in diverse genetic backgrounds. Maize Genetics Conference, 20-23 March, Beijing, China
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2014
Citation:
Ma X, Miranda L, Ahearn M, Wang Y, Lubkowitz M, Braun DM and Weil C 2014. Genetics of Carbon Partitioning in Maize. Maize Genetics Conference , 201-23 March, Beijing, China
|
Progress 10/01/12 to 09/30/13
Outputs
Target Audience: The target audiences include: 1. Students and academic researchers that are interested in expanding our knowledge of key agronomic traits in maize 2. Stakeholder groups representing input providers, farmers, and end-user groups 3. Since this research impacts both domestic and international markets, another important audience for our research is the international research community; particularly our colleagues and collaborators in the Consultative Group on International Agricultural Research (CGIAR). Changes/Problems: PROJECT MODIFICATIONS: Dr. Clifford Weil and Dr. Mitchell Tuinstra were added to this project in 2011 to enhance collaboration on these objectives and maximize potential for success. What opportunities for training and professional development has the project provided? We had three graduate students complete their PhD and now work in the private sector for AgReliant Genetics,Dow AgroSciences, and Dupont - Pioneer Hi-Bred. One graduate student completed an MS degree and is now working on a PhD. How have the results been disseminated to communities of interest? Through talks at regional, national and international professional meetings and through abstracts, and through journal publications, particularly for the nutritional traits. What do you plan to do during the next reporting period to accomplish the goals? Contine the field studies so that we can study genotype by environment interactions over more years. Perform more detailed genomic and genetic anlayses to better understand the genetic basis of some traits. Continue marker assisted selection programs.
Impacts
What was accomplished under these goals?
To understand the extent of the influence of environment on newly developed genotypes, genotypes must be tested in diverse environments using multi-environmental trials (MET) before their commercial release into a particular target environment. Modern plant breeding evaluation techniques use augmented field designs with unreplicated test genotypes in MET. We evaluated nested random regression models (NRRMs) to estimate GxE interactions and to identifying environmental indices responsible. Computer simulation studies showed that MET studies with more than 10 locations and 30 and 800 genotypes can be evaluated using these NRRM models. Based on the information obtained from NRRMs, we developed strategies for efficiently clustering locations to produce homogenous performance while commercialization of test genotypes. Based on these results, NRRMs were used to assess GxE from real METs conducted in various zones across the United States Corn Belt. These results showed that the Northern Corn Belt was most influenced by environmental characteristics during the vegetative stages while those in the Central Corn Belt were influenced by environmental conditions from the vegetative throughout the grain filling stages also. The identification of environmental factors that influence GxE and the use of these factors to clustering locations can provide better information in decision making while commercialization of chosen test genotypes. Genetic analysis of the stay-green trait was conducted in several populations of maize to define the genetic mechanisms associated this drought tolerance phenotype. In one genetic study, two advanced backcross recombinant inbred line mapping populations were created with Mo20W as one parent and B73 and Mo17 as the recurrent parents. These populations were tested under drought and high temperature stress conditions. Quantitative trait loci for the ratio vegetative index and photosystem II operating efficiency during grain fill were discovered on chromosomes one, two, three, four, six, and nine. Lines selected from the mapping populations were used in a North Carolina II experiment to evaluate hybrid expression of the stay-green trait. The hybrids exhibited higher ratio vegetative index values during the grain fill period than hybrids synthesized from Mo17 and B73. Photosystem II operating efficiency was positively correlated with grain yield across environments. In another genetic study, a subset of the maize nested association mapping population was evaluated per se and in testcross combinations with PHZ51. Joint linkage mapping discovered several quantitative trait loci for the stay-green trait in these recombinant inbred families. The results of these studies suggest that genetic diversity for functional stay-green in maize exists in both the temperate and tropical germplasm pools. The diversity for this trait could be exploited for increasing abiotic stress tolerance in maize. The overall goal of this project is to use modern genomic technologies to develop new traits and elite new public sector inbred lines and hybrids having improved performance and nutritional value. A genome-wide association study (GWAS) in the maize AMES Association Panel is being conducted to determine the genetic basis of important nutritional characteristics, component traits of yield, and plant adaption traits. The AMES Panel is comprised of more than 2,000 maize inbred lines that are stored in the USDA Germplasm Resource Information System (GRIN). The panel is being evaluated for variation in plant height and maturity, tolerance to heat and drought stresses, ear and tassel architecture traits, and nutritional traits of maize grain including content of carotenoids (VitaminA), tocopherols (Vitamin E), protein, starch, oil, and amino acids. On-going field and laboratory studies show significant genetic variation for traits measured thus far. As phenotypic and genetic data are summarized, the genetic architecture of each trait will be evaluated using GWAS techniques. Another aspect of our research in enhancement of maize focuses on analyses of the Nested Association Mapping (NAM) population for genetic variation in plant height and maturity, tolerance to heat and drought stresses, source-sink interactions and impacts on plant productivity, and grain nutritional traits. The NAM population is comprised of a series of recombinant inbred line (RIL) populations produced from crosses between 25 diverse maize populations and B73, the reference genome of maize. In 2013, a subset of the maize NAM populations with flowering times similar to B73 as well as the founder lines of each population were evaluated to identify genes and genetic loci that impact drought tolerance of maize. Ongoing plant and grain phenotyping studies show significant genetic variation in plant growth and development characteristics as well as responses to heat and drought stresses. As these data are summarized, the genetic architecture of each trait will be evaluated by nested linkage mapping and GWAS to uncover the bases of key agronomic traits. Our research activities also focus on developing a better understanding of the genetic inheritance of agronomic performance traits in private-sector corn inbred lines. Agronomic traits of interest include grain yield, grain moisture at harvest, days to anthesis, plant height, and ear height. QTL mapping populations are being developed from crosses between various exPVP lines and testcrossed to produce hybrid mapping populations. These populations are being evaluated for variations in agronomic performance in multienvironment trials. The genotypic and phenotypic information are being used in selection programs to pyramid favorable genetic loci from both parents.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Chandler, K., Lipka, A. E., Owens, B. F., Li, H., Buckler, E. S., Rocheford, T., & Gore, M. 2013. Genetic analysis of visually scored orange kernel color in maize. Crop Science. 53:189-200.
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Kandianis CB, Stevens R, Liu W, Palacios N, Montgomery K, Pixley K, White WS, Rocheford T. 2013. Genetic architecture controlling variation in grain carotenoid composition and concentrations in two maize populations. Theor Appl Genet.126(11):2879-95.
- Type:
Journal Articles
Status:
Accepted
Year Published:
2013
Citation:
Lipka AE, Gore MA, Magallanes-Lundback M, Mesberg A, Lin H, Tiede T, Chen C, Buell CR, Buckler ES, Rocheford T, DellaPenna D. 2013. Genome-wide association study and pathway-level analysis of tocochromanol levels in maize grain. G3 (Bethesda): 7;3(8):1287-99.
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Heying EK, Grahn M, Pixley KV, Rocheford T, Tanumihardjo SA. 2013. High-provitamin A carotenoid (Orange) maize increases hepatic vitamin A reserves of offspring in a vitamin A-depleted sow-piglet model during lactation. J Nutr. 2013 Jul;143(7):1141-6.
- Type:
Journal Articles
Status:
Published
Year Published:
2012
Citation:
Nuss ET, Arscott SA, Bresnahan K, Pixley KV, Rocheford T, Hotz C, Siamusantu W, Chileshe J, Tanumihardjo SA. 2012 Comparative intake of white- versus orange-colored maize by Zambian children in the context of promotion of biofortified maize. Food Nutr Bull. 33(1):63-71.
- Type:
Journal Articles
Status:
Published
Year Published:
2012
Citation:
Liu YQ, Davis CR, Schmaelzle ST, Rocheford T, Cook ME, Tanumihardjo SA. 2012. ?-Cryptoxanthin biofortified maize (Zea mays) increases ?-cryptoxanthin concentration and enhances the color of chicken egg yolk. Poult Sci. 91(2):432-8.
- Type:
Theses/Dissertations
Status:
Accepted
Year Published:
2012
Citation:
Michael Popelka. 2012. Genetic Architecture of Stay-Green in Maize. PhD Dissertation Purdue University.
- Type:
Theses/Dissertations
Status:
Accepted
Year Published:
2013
Citation:
Jason Morales. 2013. Genetic Studies on Ex-Plant Variety Protected Germplasm. PhD Dissertation Purdue University.
- Type:
Theses/Dissertations
Status:
Accepted
Year Published:
2013
Citation:
Annie Elias. 2013. Genetic Studies on Genotype x Environment Interactions
- Type:
Theses/Dissertations
Status:
Accepted
Year Published:
2013
Citation:
Tyler Tiede. 2013. Genomic Analysis of Carotenoids. M.S. Non-Thesis
- Type:
Book Chapters
Status:
Published
Year Published:
2013
Citation:
Renaud AL, Tuinstra MR. 2013. Role of Engineering Plants for Abiotic Stresses. pp 51-55. In D. Niyogi (ed.) Climate Vulnerability. Elsevier Limited, Oxford, UK.
- Type:
Book Chapters
Status:
Published
Year Published:
2013
Citation:
Yu J, Hamblin MT, Tuinstra MR. 2013. Association Genetics Strategies and Resources. pp 187-203. In AH Patterson (ed.) Genetics and Genomics of Saccharinae, Vol. 11. Springer Inc., New York. 10.1007/978-1-4419-5947-8_9.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2013
Citation:
Tuinstra MR. 2013. Drought tolerant crops. Indiana CCA Conference, 17-18 December, Indianapolis, IN.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2013
Citation:
Tuinstra MR. 2013. How can we increase crop yield under real conditions to better feed the world? Sustainability, Genetics, and Future Cultivars, AACCI Hot Topic Workshop, September 29, Albuquerque, NM.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2013
Citation:
Tuinstra MR. 2013. Dissecting heat tolerance in maize: physiological and molecular basis. Heat Tolerant Maize for Asia (HTMA) Project Annual Review and Planning Meeting, 30-31 July, Hotel Yak & Yeti, Darbar Marg, Kathmandu, NEPAL.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2013
Citation:
Tuinstra MR. 2013. GMO: Bad Reputation; Good Solution? Sustainable Foods Institute 2013, Monterey Bay Aquarium, May 15-17, Monterey, CA.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2013
Citation:
Tuinstra MR. 2013. Adapting Maize and Sorghum to Stressful Environments. 2013 NCCC-167 Meeting, Pheasant Run Resort, March 13-14, St. Charles, IL.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2013
Citation:
Tuinstra MR. 2013. Adapting Maize to Environmental Stresses. AgReliant Genetics Maize Research Meeting, Purdue University, March 12, West Lafayette, IN.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2013
Citation:
Tuinstra MR. 2013. Adapting Maize and Sorghum to Stressful Environments. Dissemination workshop of the ACIAR-funded project Improving postrainy sorghum varieties to meet the growing grain and fodder demand in India , ICRISAT, February 19-21, Hyderabad, India.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2013
Citation:
Tuinstra MR. 2013. Climate Resilient Agriculture. Wabash College, February 7, Crawfordsville, IN.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2013
Citation:
Tuinstra MR. 2013. Heat and Drought Stress Tolerance in Maize. The Corn Belt Seed Conference, Indianapolis Marriott North, February 6, Indianapolis, IN.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2013
Citation:
Tuinstra MR. 2013. Heat stress tolerant maize Purdue perspective. Heat Tolerant Maize for Asia (HTMA), Genomic Selection Workshop & Project Launch Meeting, 23-25 January, The New Sahel Conference Room, ICRISAT, Patancheru, Hyderabad, INDIA.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2013
Citation:
Tuinstra MR. 2013. Prospects for Adapting Maize to Drought and High-Temperature Stresses. Keystone Symposium on Plant Abiotic Stress and Sustainable Agriculture: Translating Basic Understanding to Food Production, Sagebrush Inn and Conference Center, January 17-22, Taos, NM.
|
Progress 10/01/11 to 09/30/12
Outputs
OUTPUTS: The overall goal of this project is to use modern genomic technologies to develop new traits and elite new public sector inbred lines and hybrids having improved performance and nutritional value. A genome-wide association study (GWAS) in the maize AMES Association Panel is being conducted to determine the genetic basis of important nutritional characteristics, component traits of yield, and plant adaption traits. The AMES Panel is comprised of more than 2,000 maize inbred lines that are stored in the USDA Germplasm Resource Information System (GRIN). The panel is being evaluated for variation in plant height and maturity, tolerance to heat and drought stresses, ear and tassel architecture traits, and nutritional traits of maize grain including content of carotenoids (VitaminA), tocopherols (Vitamin E), protein, starch, oil, and amino acids. On-going field and laboratory studies show significant genetic variation for traits measured thus far. The AMES panel has been and continues to be genotyped with denser coverage by the Buckler Lab, USDA/ARA at Cornell University. As phenotypic and genetic data are summarized, the genetic architecture of each trait will be evaluated using GWAS techniques. Another aspect of our research in enhancement of maize focuses on analyses of the Nested Association Mapping (NAM) population for genetic variation in plant height and maturity, tolerance to heat and drought stresses, source-sink interactions and impacts on plant productivity, and grain nutritional traits. The NAM population is comprised of a series of recombinant inbred line (RIL) populations produced from crosses between 25 diverse maize populations and B73, the reference genome of maize. In 2012, a subset of the maize NAM populations with flowering times similar to B73 as well as the founder lines of each population were evaluated to identify genes and genetic loci that impact performance and nutritional value of maize. On-going plant and grain phenotyping studies show significant genetic variation in plant growth and development characteristics as well as responses to heat and drought stresses. As these data are summarized, the genetic architecture of each trait will be evaluated by nested linkage mapping and GWAS to uncover the bases of key agronomic traits. Our research activities also focus on developing a better understanding of the genetic inheritance of agronomic performance traits in private-sector corn inbred lines. Agronomic traits of interest include grain yield, grain moisture at harvest, days to anthesis, plant height, and ear height. QTL mapping populations are being developed from crosses between various exPVP lines and testcrossed to produce hybrid mapping populations. These populations are being evaluated for variations in agronomic performance in multi-environment trials. The genotypic and phenotypic information are being used in selection programs to pyramid favorable genetic loci from both parents. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Maize breeders. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Genes that modify the levels and compositions of these nutritional characteristics have been identified. These genetic advances are enabling allele specific selection for increasing levels of specific compounds in corn grain. A study examined the kernel compositions of progeny from the Illinois Low Protein Populations. Results for this study have revealed significant differences for kernel starch content among genotypes. We expanded the genetic base of inference for these studies by measuring leaf chlorophyll content and kernel composition traits in the AMES corn inbred panel under various N-fertility treatments. GWAS analyses in the AMES Panel will be used to identify the genes contributing to variation in these traits. Results from these studies will contribute to developing high-starch maize hybrids for industrial applications. The digestibility of maize in the animal gut is a crucial part of how efficiently grains such as maize can be used as feed and as food ingredients. Slower digestion rates of raw corn have been correlated with more efficient animal weight gain per unit feed, while slower digestion of of cooked starch is associated with slower release of glucose into the bloodstream, lower glycemic index and human health benefits. Part of this project is focused on identifying genetic determinants of maize digestibility using in vitro assays that mimic the animal gut. We have sampled the natural diversity of maize using the NAM population to identify variants with slower digestion rates. As part of the same study we have also identified lines that show faster and higher digestion rates, which can be used to improve the efficiency of ethanol generation per unit of grain. Heat and drought stress are the most important factors affecting crop production around the world. Germplasm and trait development studies are being conducted to improve heat and drought stress tolerances. One component of our research focuses on dissecting the expression of late-season staygreen and drought tolerance of maize. QTL analyses for these traits are being conducted in the maize NAM populations to identify and pyramid favorable alleles for nutrient content and stress tolerance. Using a series of known mutants defective in carbon partitioning that have overt plant phenotypes as reporters, as well as a collection of new mutants we have created, we are using the natural diversity of maize to characterize the control of carbon partitioning from source to sink. Crossing our mutants to the well characterized founders of the NAM population we have identified lines with modifiers of our mutant phenotypes, which indicate genes that interact with the gene defective in each carbon partitioning mutant. Elite commercial corn inbred lines are being developed from crosses between ex-Plant Variety Protected (exPVP) germplasm representing important commercial parent lines. The evaluation of these exPVP derived materials showed many were competitive with commercial hybrids (Morales et al., 2012). Our work with exPVP germplasm enables us to work interactively with private seed companies on evaluation of grain yield and other important agronomic traits.
Publications
- No publications reported this period
|
Progress 10/01/10 to 09/30/11
Outputs
OUTPUTS: The overall goal of this project is to use modern genomic technologies to develop new traits and germplasm of maize. One of the key components of this project includes efforts to genetically enhance the nutritional characteristics of maize. One of the efforts is to improve carotenoid and tocopherol content. Field and laboratory trials are underway to identify genes controlling levels and forms of carotenoids and tocopherols to enable marker assisted selection for these traits. In 2011, the Ames Testcross hybrid collection was grown in multilocation trials and grain collected from these experiments are being evaluated for variation in carotenoid and tocopherol content. Another aspect of our research in nutritional enhancement of maize is to improve the digestibility of cooked corn starch as a food ingredient and of uncooked corn as livestock feed by slowing its digestion rate. During this past year the founder parents of the Nested Association Mapping (NAM) population were evaluated for digestibility characteristics in vitro and the slowest and fastest digesting lines identified. Recombinant inbred lines from the NAM population are being evaluated to identify genetic components that affect digestion rate. Another area of our research activities focuses on developing a better understanding of the genetic inheritance of agronomic performance traits in private-sector corn inbred lines. Agronomic traits of interest include grain yield, grain moisture at harvest, days to anthesis, plant height, and ear height. QTL mapping studies demonstrated numerous QTL associated with grain yield and component traits. The genotypic information is being used in selection programs to pyramid favorable QTL from both parents. Heat and drought stress are the most important factors affecting crop production around the world. To address these issues, germplasm and trait development efforts are focused on use of natural genetic variability for this trait in corn, particularly tropical germplasm, to improve stress tolerance using forward genetics strategies. One component of our research focuses on dissecting the expression of late-season staygreen and drought tolerance. Testcross hybrids of the Nested Association Mapping (NAM) populations of maize are being evaluated for phenotypes associated with grain yield, phenology, plant water relations, carbon isotope discrimination, and late-season drought tolerance in multilocation trials. Significant differences were observed for many of the traits. QTL analyses for these traits are being conducted in individual populations and across populations in combined analyses. A marker assisted selection program is being developed to pyramid favorable alleles for floral architecture, nutrient content, and stress tolerance. Favorable alleles are being introgressed into both dent and sweet corn genetic backgrounds. The outputs will be evaluated by number of potentially useful QTL detected, and whether marker assisted selection resulted in improved values for the trait under selection in lines that may be useful. PARTICIPANTS: This is a multidisciplinary and collaborative project with collaborators representing numerous public and private sector organizations. Testcross hybrids of the Nested Association Mapping (NAM) populations of maize are being evaluated in collaboration with Dr. Ed Buckler, USDA-ARS and Sara Larssen. Genetic studies to developing a better understanding of the inheritance of agronomic performance traits in private-sector corn inbred lines are being conducted in collaboration with Dow AgroScience. Drought tolerance phenotyping of maize lines, hybrids, and mapping populations are being conducted in collaboration with Pioneer Hi-Bred International. TARGET AUDIENCES: The target audiences include: 1. Students and academic researchers that are interested in expanding our knowledge of key agronomic traits in maize 2. Stakeholder groups representing input providers, farmers, and end-user groups 3. Since this research impacts both domestic and international markets, another important audience for our research is the international research community; particularly our colleagues and collaborators in the Consultative Group on International Agricultural Research (CGIAR). PROJECT MODIFICATIONS: Dr. Clifford Weil and Dr. Mitchell Tuinstra were added to this project in 2011 to enhance collaboration on these objectives and maximize potential for success.
Impacts
A genome-wide association study (GWAS) of the maize NAM population was used to determine the genetic basis of important leaf architecture traits. The genetic architecture of the leaf traits was dominated by small effects, with little epistasis, environmental interaction or pleiotropy. These results demonstrate that the use of GWAS with specially designed mapping populations is effective in uncovering the basis of key agronomic traits. In a related study, four male inflorescence traits and three female inflorescence traits were measured and studied using linkage and genome-wide association analyses. Inflorescence loci were shown to have larger effects than flowering and leaf loci, and ear effects were larger than tassel effects. Ear trait models had lower predictive ability than tassel, flowering, or leaf trait models. Pleiotropic loci were identified that control elongation of ear and tassel, consistent with their common developmental origin. For these loci, the ear effects were larger than tassel effects. Our results support the hypothesis that genetic architecture is a function of trait stability over evolutionary time, since the traits that changed most during the relatively recent domestication of maize have the largest effects. Genetic analyses of the staygreen trait in corn demonstrated significant differences in the pattern and timing of senescence among diverse inbred lines and their hybrids. Ongoing studies of near-isogenic lines contrasting for important staygreen genes are being used to quantify the impact of staygreen on agronomic performance of hybrids adapted to production in the United States. Phenotypic analyses of testcross hybrids of 1500 corn NAM lines from 22 different mapping populations demonstrated significant variation in expression of staygreen in trials conducted in North Carolina, Indiana, Iowa, and Missouri. QTL analyses indicated two major genes for hybrid staygreen. Genetic analyses show that one of these genes was derived from low-land tropical germplasm developed at the CIMMYT in Mexico and the other gene was derived from Suwan germplasm that originated in Asia. Marker assisted selection is being used to move these genes from the tropical gene pool to elite inbred lines that can be used in plant breeding and hybrid development in the United States.
Publications
- Brown, P.J., N. Upadyayula, G. Mahone, F. Tian, P.J. Bradbury, S.M. Myles, J.B. Holland, M.D. McMullen, E.S. Buckler, and T.R. Rocheford. 2011. Distinct genetic architectures for male and female inflorescence traits of maize. PLoS Genetics 7:e1002383.
- Chaikam, V., A. Negeri, R. Dhawan, B. Puchaka, J. Ji, S. Chintamanani, E.W. Gachomo, A. Zillmer, T. Doran, C.F. Weil, P. Balint-Kurti, G. Johal. 2011. Use of mutant-assisted gene identiļ¬cation and characterization (MAGIC) to identify novel genetic loci that modify the maize hypersensitive response. Theoretical and Applied Genetics 123: 985-997.
- Choe, E., and T.R. Rocheford. 2011. Genetic and QTL analysis of pericarp thickness and ear architecture traits of Korean waxy corn germplasm. Euphytica 183: 243-260.
- Hung, H.Y., C. Browne, K. Guill, N. Coles, M. Eller, A. Garcia, N. Lepak, S. Melia-Hancock, M. Oropeza-Rosas, S. Salvo, N. Upadyayula, E.S. Buckler, S. Flint-Garcia, M.D. McMullen, T.R. Rocheford, and J.B. Holland. 2011. The relationship between parental genetic or phenotypic divergence and progeny variation in the maize Nested Association Mapping population. Heredity (online ahead of print).
- Popelka M.W., G.H. Johal, and M.R. Tuinstra. 2010. Stay-green: Abiotic stress tolerance in maize Corn & Sorghum and Soybean Seed Research Conference 2010, Chicago, Illinois.
- Popelka MW, Krothapalli K, Johal GH, Tuinstra MR. 2011. Functional Stay-green: Abiotic Stress Tolerance in Maize. P219. 53rd Annual Maize Genetics Conference. 17-20 March 2011, St. Charles, Illinois, USA.
- Popelka MW, Krothapalli K, Tuinstra MR. 2011. Analysis of Stay-Green and Abiotic Stress Tolerance In Maize. Abstract 219-8. ASA-CSSA-SSSA Annual Meetings, San Antonio, TX, 16-19 October 2011.
- Tian, F., P.J. Bradbury, P.J. Brown, H. Hung, Q. Sun, S. Flint-Garcia, T.R. Rocheford, M.D. McMullen, J.B. Holland, and E.S. Buckler. 2011. Genome-wide association study of leaf architecture in the maize nested association mapping population. Nature Genetics 43: 159-162.
- Tuinstra MR, Popelka M, Krothapalli K, Johal G, Mickelbart M, Larsson S, Buckler E. 2011. Mining Genes for Late-season Drought Tolerance in Maize. International conference on crop improvement, ideotyping, and modelling for African cropping systems under climate change. 7-9 February 2011, University of Hohenheim, Euro-Forum, Stuttgart, Germany.
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