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Title: TRANSMISSION OF MAIZE CHROMOSOME 9 REARRANGEMENTS IN OAT-MAIZE RADIATION HYBRIDS

Author
item VALES, M - OREGON STATE UNIVERSITY
item RIERA-LIZARAZU, OSCAR - OREGON STATE UNIVERSITY
item Rines, Howard
item PHILLIPS, RONALD - UNIVERSITY OF MINNESOTA

Submitted to: Genome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/4/2004
Publication Date: 12/3/2004
Citation: Vales, M.I., Riera-Lizarazu, O., Rines, H.W., Phillips, R.L. 2004. Transmission of maize chromosome 9 rearrangements in oat-maize radiation hybrids. Genome. 47(6):1202-1210.

Interpretive Summary: Recent reports of the elucidation of the genetic blueprint (DNA sequence structure) of two plants, the small mustard-like plant Arabidopsis and the cereal grain rice, have provided a major step forward in understanding how plants grow and convert sun-energy to food for humans and other animals. Efforts to elucidate the genetic blueprint of our major cereal crop corn is much more challenging because its genome or total DNA sequence is several times larger than that of Arabidopsis or rice, and so novel tools are needed to assist in this formidable task. The DNA within the cells of plants and animals comes distributed in packages termed chromosomes. The basic number of chromosomes varies with species, corn has ten. Earlier we described the recovery of some unique partial hybrids between oat and corn in which a portion of the corn's genetic material, one of the ten chromosomes, is added to the complete genome of oat. We then treated such plants with gamma radiation to break the corn chromosome into segments. The resulting materials, a set of oat plants each containing only a segment or two of a corn chromosome, greatly reduces the complexity allowing analysis of the corn genome a segment at a time. Important to the value of these materials was that they could be perpetuated into offspring to maintain supplies of materials for analysis. Our studies focusing on the inheritance of rearranged versions or segments of corn chromosome 9 revealed that most transmitted in a stable fashion. This information means that these novel materials are reliably available as powerful tools by scientists working in the area of corn genomics and its application to corn genetic improvement.

Technical Abstract: Oat-maize radiation hybrids are oat (Avena sativa L.) plants carrying radiation-induced sub-chromosome fragments of a given maize (Zea mays L.) chromosome in the form of deletions, intergenomic translocations, and a combination of both. Maize chromosome 9 radiation hybrids were identified among progeny of a maize chromosome 9 monosomic addition line of oat that had been treated with gamma rays. Because first-generation radiation hybrids contain various maize-chromosome 9 rearrangements in a hemizygous condition, variation might be expected in the transmission of these rearrangements to subsequent generations. Thus, we evaluated the transmission of maize-chromosome 9 rearrangements in progenies of 30 oat-maize radiation hybrids. Normal and versions of maize-chromosome 9 with detectable deletions were transmitted at similar frequencies of 9.1% and 7.6%, respectively. Intergenomic translocations transmitted at a significantly higher frequency of 47.6%. Most of the rearrangements were re-isolated in the hemizygous condition. Homozygous lines for intergenomic translocations involving maize-chromosome 9 were identified in 5% of the progenies. These lines stably transmitted a given rearrangement to the subsequent generation. Because loss of vigor was observed in some lines, it would be advisable to cross these lines to oat to restore its genetic background.