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Title: Adding B-chromosomes of Zea mays L. to the genome of Avena sativa L.

Author
item KYNAST, RALF - ROYAL BOT. GARD., KEW, UK
item GALATOWITSCH, MARK - UNIVERSITY OF MINNESOTA
item HUETTL, PAUL - UNIVERSITY OF MINNESOTA
item PHILLIPS, RONALD - UNIVERSITY OF MINNESOTA
item Rines, Howard

Submitted to: Maize Genetics Cooperation Newsletter
Publication Type: Abstract Only
Publication Acceptance Date: 1/21/2007
Publication Date: 3/20/2007
Citation: Kynast, R.G., Galatowitsch, M.W., Huettl, P.A., Phillips, R.L., Rines, H.W. 2007. Adding B-chromosomes of Zea mays L. to the genome of Avena sativa L. [abstract]. Maize Genetics Cooperation Newsletter. p. 16.

Interpretive Summary:

Technical Abstract: B-chromosomes (Bs) are supernumerary dispensable chromosomes described in hundreds of animal and plant species, including maize (Zea mays L.). However, Bs have not been reported to exist in hexaploid oat (Avena sativa L.). In order to transfer maize Bs sexually from maize to oat genomes, we used as the male parent a backcross line of the maize inbred 'B73' harboring Bs from Black Mexican Sweet generously provided by JA Birchler, University of Missouri. From 2,341 ovaries, 115 immature F1 (oat x maize) embryos were in vitro rescued 14-15 days after pollination. A total of 31 F1-embryos germinated and developed into vigorous plantlets large enough for molecular and cytogenetic analyses. Two F1-plantlets (5811-1 and 5845-1) were found to have retained maize chromosomes in shoot tissues. PCR assays involving two B-specific markers showed the presence of maize Bs and not maize As. Cytological analyses revealed that in the F1-plant 5811-1 a complete set of 21 oat chromosomes plus three maize Bs (2n = 3x+3B = 24) were retained. In the F1-plant 5845-1 a complete set of 21 oat chromosomes and a single maize B were retained (2n = 3x+1B = 22). Cytological and molecular analyses of 20 F2-offspring plants showed that the F1-plant 5811-1 carrying 3 Bs produced three F2-plants with 1 B, six F2-plants with 2 Bs, one F2-plant with 3 Bs, one F2-plant with 4 Bs, and nine F2-plants with highly chimeric root meristems showing cells with 1-5 Bs in different frequencies. For the F1-plant 5845-1 carrying one B, none of the 10 F2-offspring tested by cytological and molecular means had Bs. Our results of 30 tested F2-offspring from 2 maize B-positive F1-plants showed that maize Bs can be transmitted to offspring even when in the presence of only oat chromosomes.