IV. MAIZE GENETICS COOPERATION STOCK CENTER

During calendar 1990, 2656 seed samples were supplied in response to 202 requests. Included were requests from 17 foreign countries. In addition, advice and information were provided particularly with regard to the classification and use of genetic stocks and relative to pedigree lineages and genetic backgrounds. Each year a substantial number of misdirected requests are received, and an effort is made to refer these to appropriate persons.

Because of a record high rainfall total during the May-June period, there were problems of seedling emergence in the early May planting and later plantings were much delayed. A late season drouth in August and September resulted in poor kernel fill in late plantings. Seed increase efforts met with varied success, largely dependent on the vigor and agronomic performance of individual stocks. In many instances, seed increases were too limited to constitute a long-term seed supply and insufficient for catalog listing prior to further increases.

Field and greenhouse plantings of the past year included the following:

(1) Stocks of miscellaneous dominant or recessive symbolized genes newly available in recent years.

(2) Extensive plantings of chromosome 1 and chromosome 4 stocks.

(3) New genes or combinations received during the past year from Cooperators.

(4) A traditional series of B-A translocations, supplemented by additional interchanges mostly located in 3L, 4L or 10L.

(5) Stocks of wx-marked translocations received from D. S. Robertson.

(6) Tetraploid stocks.

(7) A selfing block of mutant alleles expressed as kernel or seedling traits.

(8) Observation plantings for field classification.

(9) Greenhouse sandbench plantings to determine or confirm genotypes relative to seedling traits.

We are hopeful that within the next year or two supplemental cold storage facilities may become available. In that event, we plan to transfer seed samples of less-frequently requested stocks to such facilities, freeing space in our current cold room to receive additional items. Included in such transfer will be numerous multiple gene chromosome tester combinations that are occasionally requested but that no longer represent the best available tools for location of genes to chromosome and that span too long a chromosome region for effective use in detailed mapping.

Listings of catalog stock items change from year to year. Requests should be based on the most recent listing. In making written requests, you should indicate both the code number of a particular stock and its genotype. In some cases, this information allows us to recognize typographical errors directly, and in other instances non-correspondence between these two categories of information alerts us to seek clarification of your intent.

It is sometimes necessary to discontinue providing samples of particular listed items because of inadequate seed supplies or because of errors detected in pedigrees. On these occasions, in filling requests we attempt to substitute stocks with closely similar genotypes.

As you cease active work with particular genetic stocks, and while their viability is still good, we urge you to give timely consideration to whether the materials are sufficiently valuable to merit sending them to the Stock Center for continued preservation. If they involve traits that require special techniques, facilities or skills for classification (e.g., isozyme variants, resistance to pathogens), under our current capabilities it is virtually essential that the stocks be homozygous for the designated alleles so they may be propagated by selfing, sibbing or intercrossing without the necessity for classifying segregating progenies.

                                                                                                                                   E. B. Patterson
                                                                                                                                   S-118 Turner Hall
                                                                                                                                   Agronomy Department
                                                                                                                                   University of Illinois
                                                                                                                                   1102 S. Goodwin Avenue
                                                                                                                                   Urbana, IL 61801

Phone (217)-333-6631 (Lab)

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors

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