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United States Department of Agriculture

Agricultural Research Service

Research Project: CONSERVATION AND UTILIZATION OF MAIZE GENETIC STOCKS
2013 Annual Report


1a.Objectives (from AD-416):
1) Efficiently and effectively conserve and distribute a comprehensive assemblage of maize genetic stocks and associated information to maize researchers and breeders worldwide. 2) Strategically genotype and phenotype maize genetic stocks for priority traits, and incorporate genotypic and phenotypic data into MaizeGDB, GRIN, and/or other databases.


1b.Approach (from AD-416):
Our mission is to make natural and induced allelic and chromosomal variations available to the scientific community and to make information about the mutant collection available to researchers. The National Plant Germplasm System provides support to selected genetic stock centers having genetic resources of value to U.S. agricultural interests. The Maize Genetics Cooperation - Stock Center maintains important accessions of morphological and physiological markers, aneuploid material, translocations and inversions that are important tools in biological research. This project will increase the value of the stock collection as genetic tools and confirm the status of novel mutants discovered. Maize mutants have historically been used in gene discovery and will continue to be used in this way. New mapping tools in our collection will allow easier identification of genomic sequence underlying a phenotype. More recently, novel genes are being identified purely by sequence analyses. This will excel in the next few years with the release of the maize genome sequence. Identification of the functions for these newly identified genes can be determined by researchers with reverse genetics resources in our collection.


3.Progress Report:
69,800 seed samples have been supplied in response to 1,746 requests. These include 541 requests received from 28 foreign countries. Characterization of stocks by allele testing. This is useful to determine if traits of uncharacterized stocks are allelic to known genes, or if they are novel traits. We conducted allelism tests of several categories of mutants with similar phenotype or chromosome location. We further characterized a system of maize aleurone color enhancers and published a paper on the results. Further characterization of new corn mutants. It is useful to determine if traits of these mutants are due to defects in known genes, or if they are novel traits. We conducted tests on several categories of mutants with similar effects on the corn plant and/or found to be located in a similar position on a chromosome. We identified additional mutant variants of five genes. We have characterized additional variants of regulatory genes that function to enhance kernel color. These genes regulate pigment synthesis in the corn kernel. Identification of a marker useful for selecting maize haploids (contains half the normal number of chromosomes; a doubled-haploid is a much more efficient way to create new inbred lines). We have characterized dominant yellow-green corn seedling/plant mutants. Most were found to be lethal as homozygotes (when made true-breeding), but one was completely viable and expresses well in both early seedlings and adult plants and would be easily scorable in selecting for haploids. The dominant yellow-green gene will be of interest in understanding plant metabolism (e.g., photosynthesis). Its use in haploid selection will allow more efficient breeding to develop new inbred lines. These studies will enhance maize biological research and lead to agronomic improvements in this crop plant.


4.Accomplishments
1. Characterization of stocks by allele testing. This is useful to determine if traits of uncharacterized stocks are allelic to known genes, or if they are novel traits. We conducted allelism tests of several categories of mutants with similar phenotype or chromosome location. This will enhance maize biological research and lead to agronomic improvements in this crop plant.

2. Further characterization of new corn mutants. It is useful to determine if traits of these mutants are due to defects in known genes, or if they are novel traits. We conducted tests on several categories of mutants with similar effects on the corn plant and/or found to be located in a similar position on a chromosome. We identified additional mutant variants of five genes. We have characterized additional variants of regulatory genes that function to enhance kernel color. These genes regulate pigment synthesis in the corn kernel. This will enhance corn biological research and lead to agronomic improvements in this crop plant.

3. Identification of a marker useful for selecting maize haploids. We have characterized dominant yellow-green corn seedling/plant mutants. Most were found to be lethal as homozygotes (when made true-breeding), but one was completely viable and expresses well in both early seedlings and adult plants and would be easily scorable in selecting for haploids. The dominant yellow-green gene will be of interest in understanding plant metabolism (e.g., photosynthesis). Its use in haploid selection will allow more efficient breeding to develop new inbred lines. This will enhance corn biological and agricultural research by giving us a greater understanding of metabolism and useful tools to enhance breeding.


Last Modified: 12/19/2014
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