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United States Department of Agriculture

Agricultural Research Service

Research Project: GENETIC ANALYSIS OF SELECTION RESPONSE IN MAIZE POPULATIONS
2008 Annual Report


1a.Objectives (from AD-416)
Our overall goal is to determine the genetic foundation for morphological and compositional characteristics that enhance agronomic performance and quality of maize grain and stover. We will also develop new tools for measuring economically important traits in maize. For the next five-year research cycle we will:

Objective 1: Identify key morphological phenotypes and the underlying genes and/or genetic systems that have contributed to improvement in grain yield and other important agronomic phenotypes in maize. Objective 2: Develop new tools for evaluating and identifying maize varieties with superior properties for bioenergy production. Objective 3: Identify key physiological and biochemical phenotypes and the underlying genetic systems that have contributed to improvement in methionine content and bioenergy potential.


1b.Approach (from AD-416)
Objective 1: We will map genomic regions and attempt to identify candidate genes for morphological phenotypes that may have changed in response to selection for agronomic performance in the Iowa Stiff Stalk Synthetic population. We will focus on three morphological phenotypes, silking-anthesis interval, leaf angle, and number of ears per plant. We will determine the magnitude of selection response for these traits in Iowa Stiff Stalk Synthetic population and determine if any of these are correlated to agronomic traits in the base population. We will then use advanced cycles of selection and the base population to generate a genetic mapping experiment to determine how many regions and what magnitude of effects those regions have for the morphological traits. We will use all of the information collected to determine if response to selection for agronomic traits can be explained by indirect response for morphological characters. Objective 2: One method of production of biofuel from plant material involves fermentation, which is dependant on the production of sugars from the plant material. We will develop methods for screening varieties for their ability to produce sugars in small scale processes that mimic current methods being used for production of ethanol. Sugars will be quantified using bacterial biosensor strains we will develop using bacterial genes known to respond to sugar levels. Objective 3: We will characterize the genetic mechanism controlling production of methionine by biochemical analysis of populations selected for high and low methionine. In addition, we will determine if different genetic mechanisms controlling methionine levels are complimentary by combining them genetically and determining the methionine levels in the different genetic combinations.


3.Progress Report
During the three months this project has been in place, we have carried out planning activities and planted seed fields required for the project. We are gearing up laboratory work by testing methods. This research fits within NP 301 Action Plan, Component #3, Genetic Improvement of Crops, Problem Statement 3A: Genetic Theory and Methods of Crop Improvement, 3B, Capitalizing on Untapped Genetic Diversity and Component #2, Crop Informatics, Genomics and Genetic Analyses, Problem Statement 2C, Genetic Analysis and Mapping of Important Traits. Objective one seeks to correlate morphological traits with agronomic traits and regions of the genome, increasing our understanding of the genetics controlling crop yields and enabling development of new methods for crop improvement. Objectives 2 and 3 focus on understanding the genetics of valuable traits including suitability for biofuel production and grain methionine content, and use untapped genetic diversity to improve these traits.


4.Accomplishments
1. Development of a sugar-consuming biosensor for evaluation of biomass.

Fermentation of lignocellulosic biomass will likely be important in meeting the nation’s demand for liquid biofuel. Development of improved sources of biomass will increase the effectiveness of this strategy, however in order to do this, a method for evaluation of biomass is required. We developed a method that predicts the suitability of biomass feedstocks for fermentative biofuel production from lignocellulosic feedstocks. This technology is being used in maize breeding programs to develop varieties that yield more biofuel per area of land. This will increase our domestic biofuel production. The environment will also benefit as less area will be required to produce biomass to meet our liquid fuel needs. This accomplishment addresses National Program 301 Component 3, (Genetic Improvement of Crops), Problem Statement 3B, (Capitalizing on Untapped Genetic Diversity) by providing a method for evaluation of germplasm. This will allow us to incorporate germplasm with value for biofuel production into breeding programs. It also addresses Component 2, (Crop Informatics, Genomics and Genetic Analysis), Problem Statement 2C (Genetic Analysis and Mapping of Important Traits) by providing a method for phenotypic analysis. When applied to genetic mapping populations, this method will allow us to identify genes controlling suitability for biofuel production.


5.Significant Activities that Support Special Target Populations
None.


6.Technology Transfer

None

Review Publications
Lorenz, A., Scott, M.P., Lamkey, K.R. 2007. Quantitative determination of phytate and available phosphorus for maize breeding. Crop Science. 47:600-604.

Lorenz, A., Scott, M.P., Lamkey, K.R. 2008. Genetic variance and breeding potential of phytate and inorganic phosphorus in a maize population. Crop Science. 48:79-84.

Last Modified: 10/25/2014
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