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Maize COOP Information

[maize kernels showing variegation]The Maize Genetics Cooperation • Stock Center is part of the National Plant Germplasm System (NPGS) and is supported by the U.S. Department of Agriculture, Agricultural Research Service (USDA/ARS). Our facilities are provided by the Department of Crop Sciences of the College of Agriculture, Consumer and Environmental Sciences at the University of Illinois, Urbana/Champaign.

We specialize in maize genetic stocks. Other types of maize germplasm is provided by the North Central Regional Plant Introduction Station (NCRPIS). Both maize genetic stocks and germplasm held at (NCRPIS) are listed in the Germplasm Resources Information Network (GRIN). Maize germplasm can also be obtained from Centro Internacional para Mejoramiento de Maiz y Trigo (CIMMYT).

Detailed information about our genetic stocks and the mutations that they carry are listed in the Maize Genetics and Genomics Database (MaizeGDB)


[maize tassel seed]The Maize Genetics Cooperation originated at an evening get-together in Rollins A. Emerson's hotel room during the December 1928 American Association for the Advancement of Science (AAAS) conference in New York. During that meeting a dozen or so maize workers discussed the current state of maize linkage maps. Following this meeting, a letter summarizing both published and unpublished maize linkage data was compiled by Emerson and his student George Beadle and sent to students of maize genetics in April 1929 (now considered to be the first issue of the Maize Genetics Cooperation • News Letter). The formal organization of the Maize Genetics Cooperation occurred in August 1932, when maize geneticists attending the 6th International Genetics Congress agreed to establish a cooperative enterprise to further the advance of maize genetics. Among the aims of this organization was the collection and dissemination of unpublished data and information to interested workers and the maintenance and distribution of tester stocks. The establishment of the Maize Genetics Cooperation promoted the sharing of genetic marker stocks that have been developed by maize geneticists over the years in a spirit of cooperation and generosity. A collection of stocks was assembled and maintained, and samples were supplied on request. Information was exchanged through the medium of an informal Maize Genetics Cooperation • News Letter. Both aspects of this cooperation continue to the present day.

Marcus M. Rhoades was asked to serve as the first custodian of the Maize Genetics Cooperation (1932 - 1935). Other custodians during the period at Cornell University were Rollins A. Emerson (1935 - 1936, 1940, 1941 - 1944), Derald G. Langham (1936 - 1939), Allan C. Fraser (1940 - 1941), Robert L. Cushing (1945 - 1946), and Harold H. Smith (1946 - 1952). After the Stock Center moved to Illinois, the News Letter was edited by Herbert L. Everett (1953) and Harold H. Smith (1954 - 1955). When Marcus Rhoades again became secretary, the News Letter also moved to the University of Illinois (1955) and then, with him, to Indiana University (1959 - 1974). Ed Coe, USDA/ARS & University of Missouri-Columbia, served as secretary from 1975 - 2000. Presently, Jim Birchler and Mary Schaeffer serve as co-secretaries of the Maize Genetics Cooperation • Newsletter.

[maize mutant seedlings]In 1953, Marcus Rhoades and Earl Patterson moved the collection of maize stocks from Cornell University to the University of Illinois in Urbana. The Maize Genetics Cooperation • Stock Center has been a major part of the UI Department of Agronomy (as of August '95, Department of Crop Sciences) since then, being directed by its faculty members. Initially the stocks were maintained here by Earl B. Patterson (1953-1966), then by Robert J. Lambert (1966-1982), followed by Gilbert B. Fletcher (1982-1986) and then again by Earl B. Patterson (1986-1992). Office, laboratory, cold storage, field space and greenhouse facilities are provided by the University of Illinois.

The Rockefeller Foundation initially supported the Stock Center (and Newsletter) from 1934 to 1953. During the period from 1953 to 1981 operating funds for the Stock Center were provided by grants from the National Science Foundation. Beginning in 1982, most operating funds were provided by the Agricultural Research Service, U. S. Department of Agriculture (USDA/ARS). The Maize Genetics Cooperation • Stock Center continues to be housed in the UI Department of Crop Sciences (formerly Agronomy), and in 1992, ARS took over the day-to-day operations of the Stock Center and an ARS scientist was appointed as Director. In 1993, an ARS support scientist was appointed to serve as Curator. Presently, Marty Sachs serves as Director and Jeff Gustin serves as curator. Other USDA/ARS staff members, Shane Zimmerman (Ag. Res. Tech.) and, Josh Tolbert (Information Technology Specialist) are also essential in running the Stock Center. We mourn the loss of our colleague and friend Philip Stinard, who served as curator from 1993-2019. Janet Day Jackson, also worked with the Stock Center from 1989-2010.

The collection at Cornell University consisted mostly of individual mutant genes and chromosome tester combinations useful in locating genes to chromosome and developing linkage maps.

[maize terminal ear]In September 1952, during attendance at the American Institute of Biological Sciences meeting at Cornell University, Professors Ernest G. Anderson and Marcus M. Rhoades used the opportunity to personally select seed samples of 220 stocks for transfer to the University of Illinois to serve as the nucleus of a continuing collection. At the time, numerous additional stocks were held by other geneticists in their private collections.

In 1953 the first plantings at the University of Illinois were made of the Cornell source stocks together with numerous additional stocks hurriedly solicited and assembled from other sources. Stocks are still being added to the collection each year.

The genetic stock collection

Most of the variants in the Maize Genetics Cooperation • Stock Center's collection have been recognized by maize geneticists and saved by them. Maize breeders also notice many mutant traits and submit seed samples for evaluation and potential addition to the collection.

Maintenance of maize genetic stocks is very labor intensive. Features of the maize plant that make self- or cross-pollinations simple also make hand pollination mandatory if controlled crosses are to be made. Seed samples are increased by hand pollinations. Ears are shelled individually, and the seed samples from each are stored in packets labeled with pedigrees in the form of genetic symbols. Long-term storage is in a cold room maintained at about 45° F (8° C) and at less than 30% relative humidity. Some samples of good quality seed placed immediately into these storage conditions have shown good viability after as many as 20 years. However, as a general practice efforts are made to perpetuate fresh seed stocks within a ten-year period.

[maize old gold stripe]The total collection now has over 100,000 individually pedigreed samples. The bulk of the current collection consists of several hundred symbolized genes, together with many additional gene combinations and other heritable variants. Many of the stocks are maintained in forms or combinations suitable for specific research uses. Included are about 1000 chromosome aberrations (e.g., translocations and inversions) as well as stocks varying in chromosome number (e.g., trisomic aneuploids) and complete sets of chromosomes (e.g., tetraploids). Mutant genes are also maintained that generate unbalanced chromosome complements.

Maize occupies a pre-eminent position among higher plants with regard to its excellence as a test organism for cytogenetic investigations, studies that correlate gene transmission with observable features of the physical chromosomes. A significant feature of the maize collection is the large number of chromosome aberrations that are included. Many of these were deliberately induced by various forms of radiation prior to the mid-1940's. The great majority of them, however, were induced in seed samples exposed to atomic bomb tests at Bikini Atoll in 1946 or Eniwetok Atoll in 1948. Through the years, important contributions in assembling and maintaining stocks of chromosome aberrations have been made by geneticists at the University of Missouri, Iowa State University and Indiana University.

The services provided

The Maize Genetics Cooperation • Stock Center is now the main repository for maize mutants utilized in research and development by cooperators worldwide. It is an essential resource to maize scientists conducting basic and applied biological research to produce knowledge and to develop new public or commercial varieties. The Stock Center is designed primarily to provide a service to all maize cooperators by assembling, perpetuating and supplying seed samples for use in research and development in both the public and commercial sectors. It is the goal of the Maize Genetics Cooperation • Stock Center to acquire, maintain, and make available, stocks containing all known allelic and cytological variation in maize and information about them. Any available stock(s) will be sent upon request without charge and with no obligations or restrictions on the recipient's use of the mutant(s). It is the policy of the Maize Genetics Cooperation • Stock Center not to accept stocks encumbered by restrictions of an MTA, IP or other proprietary rights.

[maize albescent]In order to allow more effective communication of maize genetics information and to allow for easier methods for scientists to request stocks from us, there is a need to develop a database for maize genetic stocks and to integrate the information into the national computer information resource network dealing with germplasm and genetic stock collections. In this regard, we have been collaborating with the Maize Genome Database (MaizeGDB). This database contains information about maize mutants and chromosomal aberrations as well as their use in biological research. Data about our stocks is entered into MaizeGDB (and also with GRIN [Germplasm Resources Information Network]) to allow users access to the latest information about available maize genetic stocks. Presently, our list of available stocks is accessible via the world wide web. With the help of Quinn Sinnott, data on available maize genetic stocks has also been entered into GRIN. A list of available stocks, by genetic symbols, will continue to be published annually as part of the Maize Genetics Cooperation • Newsletter, which is distributed to about 1000 scientists and libraries throughout the world. These listings serve as a basis for seed requests. During past few years, we averaged approximately 3,000 seed samples supplied in response to 300 requests. These totals include 700 seed samples provided in response to 65 requests from 25 foreign countries.

[maize ear mutants]In addition to traditional methods for requesting stocks (mail, phone, FAX and more recently e-mail), a user can now find a stock of interest in an on-line database and directly request stocks using a web-based order-form. The request is then transmitted electronically through the internet to us. We presently have this capability through our web site. More recently, with the help of Trent Seigfried, a 'shopping-cart' feature has been added to our individual stock listings in MaizeGDB, and also to our on-line stock catalog. This 'shopping-cart' is tied into our on-line order-form.

The value of the stocks

While the vast majority of the mutants in the collection may be too extreme for commercial use, and they are not usually evaluated and maintained with a view to their direct use in improving agricultural production or products, some of the mutants in our collection clearly have had, and may in the future have, a major impact of commercial importance. These include the white endosperm mutants, several of the mutants involved in starch biosynthesis (e.g., su1 and sh2 have been important in sweet corn production, wx1 gives starch high in amylopectin, ae1 gives starch high in amylose), and ig1 for use in making doubled haploids enabling the rapid production of new inbred lines or placing a desired inbred genotype into a new cytoplasmic background (e.g., male sterile).

[silkless female sterile mutant]However, the vast majority of mutants in our collection are likely to be useful primarily to serve as tools for basic research; in this use it is important that the traits be clearly classifiable, that is, somewhat extreme. Mutant alleles are useful to maize scientists in many different areas of research. These mutations act as coordinates on genetic or physical maps of the maize genome. In addition, many define critical steps in metabolic, developmental, and other pathways of great interest to geneticists, physiologists, breeders, molecular biologists, chemists and other plant scientists. Mutant traits may be studied directly to investigate metabolic blocks in biosynthetic pathways or, alternatively, they may be used as tools for such purposes as locating or localizing genes or control of particular chromosome segments in transmission. These mutants give maize scientists a greater understanding of corn as a biological organism and thus can lead to applications that will improve corn agronomically. Genetic stocks represent the working stocks of maize geneticists and this project provides a service to geneticists, breeders, and other biologists similar to that provided to chemists by chemical supply houses.

The true impact of the service is measured by its contribution to the sum total of knowledge. Applications flow from this knowledge. There is little doubt that the operation of this service vastly increases the efficiency and overall productivity of the maize genetics community.

Changing requirements and future planning

A steady influx of new stocks can be anticipated. In the next few years it will be particularly important to rescue and maintain valuable stocks whose perpetuation is imperiled by imminent retirements of maize geneticists. In this regard, a second low-humidity coldroom was built (1993), essentially doubling our seed storage capacity. This additional capacity found immediate use for storage of seed samples that were held at room temperature pending availability of supplementary long-term storage. The second cold room has also quickly served as a repository for additional maize collections. We have obtained stocks from the collections of Barbara McClintock, Marcus Rhoades, George Sprague, and Donald Robertson, Gerry Neuffer, and Walton Galinat. We expect the collection to continue expanding considerably over the next few years to accommodate the collections of maize geneticists retiring from active research. We have also had an enormous increase in our collection from tagged mutants generated from the NSF funded Maize Gene Discovery, DNA Sequencing, and Phenotypic Analysis project and other maize genome projects and expect many more additions in the near future. To help with that, in 2007, a third seed storage room was built, that essentially doubled our storage capacity again.

It is the policy of the Stock Center that all mutants donated to the Stock Center are considered as being in the public domain, and may be provided to any requester with no restrictions or limitations; the recipient may use and transfer the mutant(s) freely in his/her research, including for the development and sale of commercial products, with no obligation to either the Stock Center or the original donor.

[zebra striped mutant]In continuing our quest to keep information up-to-date and readily accessible by members of the maize research community, we have purchased Macintosh computers that are hooked into the internet. We are accepting stock requests via e-mail ( and via a request form on our web site (our URL is We are in the process of entering stock pedigree and availability data into our internal database. This information will make pedigree analysis and planting decisions easier. It is anticipated that computerizing the Stock Center's data will enable us to enhance our service to the maize research community.

Increasingly, the distinctions between molecular genetics and biochemistry are becoming blurred. There is a continuing need to assess the role of this project relative to other programs dealing with isozymes, molecular markers, gene libraries, the maize genome projects, etc. The Maize Genetics Stock Center program should continue to serve not just as a gene source but rather as a genetic resource, with the goal of contributing increasingly to the efficiency and quality of maize genetics research. Research programs are being established at the Maize Genetics Cooperation • Stock Center. Our goal is to establish a center for Maize Genetics research that will enhance our service to the entire maize genetics, plant breeding, and biotechnology community.