DNA clones in the public bank and distribution center at the UMC Maize RFLP Lab now total over 6400, of which we distribute more than 4700 (Table 1). This includes the large sets of sequenced cDNAs generated by Chris Baysdorfer, California State University - Hayward (designated csu), and by Tim Helentjaris (designated uaz or 5C, 6C, etc.), which represent the largest collection of candidate genes publicly available for maize. Over the last four years the UMC Maize Probe Bank has filled more than 540 requests for more than 16,000 clones to 31 countries, including 71 sets of the UMC Core Marker probes (Table 2), which have become the standard landmark probe set for gene and QTL trait mapping in maize. The UMC Core Marker set has become the standard landmark set for mapping genes, phenotypes and QTLs in maize. We are particularly pleased with the growth of interest in using maize clones in "developing" countries. During the period 1993-1996 we received a total of 69 probe requests, including 15 requests for core marker probe sets, from scientists in 15 "developing" countries for a total of 3338 probes distributed. China (PRC) led the list with a total of 1601 probes requested and received. The number of probes sent to scientists in China has increased each year, indicative of the continuing demand for probe distribution. Brazil was second with 979 probes requested. Third in probes requested was Mexico. In addition to the probe banking and distribution functions, the UMC RFLP Lab will place on the UMC Maize map any clones of defined function contributed by individual scientists. This greatly enriches the UMC Maize Genetic Map as a tool to define correlations of sequence to function. To date, we have placed 250 loci from 193 different "contributed" probes. Information about genes, probes, and maps is constantly updated on MaizeDB. Most of the sets of clones of other species being held by us are a backup to their primary storage site and for our use in cross-species mapping experiments.
Three major, current research efforts will have a major impact on probe resources for maize. The first is the development of SSR probes. The current total of available SSR primer sets for maize is 195. This number is increasing due to the efforts of Lynn Senior, USDA-ARS; Ben Burr, Brookhaven Natl. Labs., and others. As this number expands, coverage of the genome will soon reach a stage that some of the applications currently conducted with RFLPs may be replaced with SSRs. The second development is the expanded use of AFLP technology. For many private and large scale public efforts the cost effectiveness of AFLPs is very attractive. The major drawback for maize is the lack of codominant information for most AFLP alleles. The third development is the initiation of large-scale EST sequencing projects for maize. Four different private concerns are reportedly sequencing greater than 100,000 ESTs for maize. While the sequences and clones are currently being held as proprietary information by the companies, these efforts or a public EST effort in maize have the potential to place into the public sector a number of defined sequence probes much greater than currently available.
The activities of the RFLP Lab and the Probe Bank are meaningful as they contribute to the research needs of the community. The easiest avenue to request clones is through the "PROBE Requests" form in MaizeDB http://www.agron.missouri.edu or by email to firstname.lastname@example.org.
To contribute clones for distribution or to be mapped onto the UMC Maize Genetic Map contact Theresa Musket at the email listed above and she will inform you of the information and materials needed.
These activities are supported by USDA-ARS CRIS projects "Genetic Mechanisms and Molecular Genetic Resources for Corn" and "Maize Genome Database"; supplemental support from USDA Plant Genome and Germplasm Programs; USDA-NRI Plant Genome Panel Grant, "Maize cDNAs and Mutants Mapped in Concert; FAO/IAEA Coordinated Research Program, "Molecular Markers for Maize, Rye and Rice", and helpful contributions from CIMMYT, DeKalb Genetics Corporation, Monsanto-Ceregen, Mycogen Plant Sciences, and Pioneer Hi-Bred International Inc.
Table 1. Clones maintained by UMC RFLP Lab and Probe Bank.
|Clone Set||Abbreviation||Type of Clone||Total Number in Set||Distribution by UMC|
|Brookhaven National Laboratories||bnl||maize genomic||109||Yes|
|Brookhaven National Laboratories||bnl||maize cDNA||12||Yes|
|California State University-Hayward||csu||maize cDNA||1197||Yes|
|Cornell University||bcd, cdo, rg, rz||barley, oat, rice||151||No|
|Iowa State University||isu||maize cDNA||136||Yes|
|Mycogen Plant Sciences||agr||maize cDNA||413||Yes|
|Contributed Clones||mostly maize||165||49 Yes, 116 No|
|Pioneer Hi-Bred International||php||maize genomic||161||Yes|
|Pioneer Hi-Bred International||npi||maize both||236||Yes|
|Rice Genome Research Program||rgp||rice||371||No|
|Texas A&M University||txs||sorghum genomic||145||No|
|University of Arizona||uaz 5C, 6C, 7C||maize cDNA||1920||Yes|
|University of Hohenheim||Ch6S||maize genomic||339||No|
|University of Minnesota||umn||oat||29||No|
|University of Missouri||umc||maize both||249||237 Yes, 12 No|
|University of Missouri-Rice||pOs||rice genomic||18||Yes|
|University of Missouri-Rye||ScG||rye genomic||171||Yes|
|University of Missouri-Tripsacum||tda||tripsacum genomic||476||20 Yes, 456 No|
|Total Number of Clones:||6413|
|Total Distributable Clones:||4752|
Table 2. Clone distribution.
|No. of Requests||No. of Clones||No. of Core Sets||No. of Requests||No. of Clones||No. of Core Sets||No. of Requests||No. of Clones||No. of Core Sets||No. of Requests||No. of Clones||No. of Core Sets|
Theresa Musket, Georgia Davis, Mary Polacco, Mike McMullen, and Ed Coe
to the MNL 71 On-Line Index
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