Skip to main content
ARS Home » Midwest Area » St. Paul, Minnesota » Plant Science Research » Research » Publications at this Location » Publication #158614
Title: DISSECTING THE MAIZE GENOME USING CHROMOSOME ADDITION AND RADIATION HYBRID LINES

Author
item KYNAST, RALF - UNIVERSITY OF MINNESOTA
item OKAGAKI, RON - UNIVERSITY OF MINNESOTA
item GALATOWITSCH, MARK - UNIVERSITY OF MINNESOTA
item GRANATH, S - UNIVERSITY OF MINNESOTA
item JACOBS, MORRISON - UNIVERSITY OF MINNESOTA
item STEC, ADRIAN - UNIVERSITY OF MINNESOTA
item Rines, Howard
item PHILLIPS, RONALD - UNIVERSITY OF MINNESOTA

Submitted to: Proceedings of the National Academy of Sciences (PNAS)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/20/2004
Publication Date: 6/29/2004
Citation: Kynast, R.G., Okagaki, R.J., Galatowitsch, M.W., Granath, S.R., Jacobs, M.S., Stec, A.O., Rines, H.W., Phillips, R.L. 2004. Dissecting the maize genome using chromosome addition and radiation hybrid lines. Proceedings of the National Academy of Sciences USA. 101(26):9921-9926.

Interpretive Summary: Corn, as the major cereal crop in the U.S. and the object of a large seed production industry, has much public and private research devoted to its genetic improvement. Yet the large size and complexity of the genome, or total genetic material, of corn has limited the ability of geneticists to determine the complete sequence and organization of the DNA comprising the corn genome, and thus their ability to fully apply tools of modern genetic research. Recently we have developed novel materials that enable dissecting the corn genome into smaller pieces which can then be characterized much more readily. These materials are a series of plants of oat, another cereal grain, which have incorporated into their genomes small segments of the corn genome. As a first step, oat plants were crossed with corn plants and offspring recovered that had a complete genome of oat but only a portion of the corn genome. This portion was one of the ten chromosomes or physical entities that comprise a corn genome. We now have a series of oat plants containing individually each of the ten corn chromosomes. The second step was to treat seed of these plants with ionizing radiation to dissect or break up the chromosomes into smaller segments. When we took a set of such plants with different segments of a single corn chromosome and compared the amount of total DNA in each segment to the number of putative genes present, we found that there was an uneven distribution of genes along the chromosome with the highest frequencies toward the ends of the chromosomes. This information together with other information gathered and the materials themselves will be highly useful to corn geneticists trying to determine the structure and organization of the corn genome to manipulate it in breeding improved corn hybrids. These materials also serve to add small sets of corn genes to oat as a possible way to genetically improve oat.

Technical Abstract: We have developed as derivatives from crosses of hexaploid oat (Avena sativa L.) x maize (Zea mays L.) 50 lines of oat that have as disomic additions individual maize (Zea mays L.) chromosomes 1 to 9 as whole chromosomes and chromosome 10 as a short-arm telosome. Whole chromosome 10 has been added to haploids of oat. Most of the maize chromosomes in disomic addition lines have regular transmission; however, chromosome 5 showed diminished paternal transmission and chromosome 10 was only transmitted to offspring as a short-arm telosome. To further dissect the maize genome, we irradiated monosomic additions with gamma rays and recovered radiation hybrid (RH) lines providing low to medium resolution for most of the maize chromosomes. For maize chromosome 1, mapping 45 SSR markers developed ten groups of RH plants with different chromosome breaks. GISH revealed the physical size of a distal region as being about 20% of the length of the short arm representing about one-third of the genetic chromosome 1 map. The present chromosome 1 RH panel dissects this chromosome region into six physical segments defined by eight groups of RH lines. The distal region of maize chromosome 1 long arm being about 20% of its length is represented by one group of RH lines, which spans more than 23% of the genetic map. These oat-maize radiation hybrids provide valuable tools for physical mapping of the complex highly duplicated maize genome and for unique studies of interspecific gene interactions.